EXAM 1 PHYSICS

(A) no, (B) yes

(A) Can two force vectors of unequal magnitude sum to zero net force? (B) Can three force vectors of equal magnitude sum to zero net force? (A) yes, (B) no (A) yes, (B) yes (A) no, (B) yes (A) no, (B) no

12.

A vector of magnitude 20 is added to a vector of magnitude 25. The magnitude of this sum might be 0. 3. 12. 47. 50.

B.There is no force on the spring

The strong man is pulling the spring apart. Is there a net force on the spring? A.Of course there is B.There is no force on the spring

All three trajectories have the same initial vertical velocity component at launch.

Three trajectories labeled A, B, and C are shown below. For which trajectory is the vertical velocity component at launch the greatest? more1_thetrajectories.gif A B C All three trajectories have the same initial vertical velocity component at launch. More information is needed to answer the question.

15 m/s to the left

Two blocks of mass M and 3 M are placed on a horizontal frictionless surface. A light spring is attached to one of them, and the blocks are pushed together with the spring between them. A cord holding them together is burned, after which the block of mass 3 M moves to the right with a speed of 5 m/s. What is the speed of the block of mass M? h5_twoblocks.gif 5/3 m/s to the left 15 m/s to the right 1/3 m/s to the right 1/3 m/s to the left 15 m/s to the left

were moving with momenta equal in magnitude and opposite in direction.

Two carts A and B are moving towards each other as shown in the diagram. They collide and come to rest at the point of impact. From this observation we can conclude that the carts a5_twocarts.jpg were moving with momenta equal in magnitude and opposite in direction. were moving with equal kinetic energies. have equal masses. were moving with velocities equal in magnitude and opposite in direction. collided elastically.

(i) D, (ii) B, (iii) N

Two carts on an air track are pushed towards each other. Initially, cart 1 moves in the positive x direction and cart 2 moves in the negative x direction. They bounce off each other elastically. The graphs at the right describe some of the variables associated with the motion as a function of time. For the experiment described and for each item in the list below, identify which graph is a possible display of that variable as a function of time. If none apply, choose N (for none). (i) the momentum of cart 1 (ii) the position of cart 1. (iii) the position of cart 2. h5_twocartsonanairtrack.gif (i) B, (ii) D, (iii) A (i) D, (ii) B, (iii) N (i) D, (ii) N, (iii) B (i) F, (ii) A, (iii) D (i) B, (ii) E, (iii) C

90.6 N

Two children pull a sled as shown. The sled moves with constant velocity v. Find the frictional force on the sled. h3_twochildren.gif 90.6 N 50 N 45 N 42 N 0 ****constant velocity in red******

0.25

Two cylindrical artificial bones are made of the same material and length, one with twice the radius as the other. When the two have the same tension force applied, the larger bone stretches by what factor compared to the smaller bone 4 2 1 0.5 0.25

(i) #1, (ii) #3, (iii) #6, (iv) #2

Two identical carts labeled A and B are initially resting on an air track. The coordinate system for describing the system is shown. The cart on the right, cart B is given a push to the left and is released. The clock is then started. At t = 0, cart B moves in the direction shown with a speed v0. They hit and stick to each other. The graphs below describe some of the variables associated with the motion as a function of time. For the experiment described and for each item in the list below, identify which graph is a possible display of that variable as a function of time assuming a proper scale. "The system" refers to carts A and B together. (i) the momentum of cart A (ii) the momentum of cart B (iii) the total momentum of the system (iv) the total kinetic energy of the system h5_twoidenticalcarts.gif (i) #1, (ii) #2, (iii) #3, (iv) #4 (i) #1, (ii) #3, (iii) #5, (iv) #2 (i) #2, (ii) #3, (iii) #5, (iv) #6 (i) #1, (ii) #3, (iii) #6, (iv) #2 (i) #4, (ii) #3, (iii) #6, (iv) #1

A.In the positive x-direction

A "motion diagram" is shown. It is a series of snapshots of a bunny's position taken every 1.0 seconds. What is the direction of the acceleration vector if the bunny is moving to the left? A.In the positive x-direction B.In the negative x-direction C.The acceleration is zero D.The acceleration does not have a direction

The ratio v1/v2 is equal to 2/5.

A 10 kg and a 4 kg mass are acted on by the same magnitude net force (which remains constant) for the same period of time. Both masses are at rest before the force is applied. After this time, the 10 kg mass moves with a speed v1 and the 4 kg mass moves with a speed v2. Which of the following is true? The ratio v1/v2 is equal to 2/5. v1 is equal to v2. The ratio v1/v2 is equal to (2/5)2. The ratio v1/v2 is equal to 5/2.

60 kW

A 1200 kg car's speed changes from 0 to 20 m/s in 4 s. What is the average power of the car motor during this time period? Neglect friction. 12 kW 60 kW 3 kW 24 kW 1200 W

6259 N

A 1400 kg car accelerates uniformly from rest to 60 mph in 6 s. Find the net force needed to produce this motion. 14000 N 233 N 6259 N 84000 N 1400 N

6/5 m, 4/5 m

A 2 kg mass is at x = 0 m, y = 2 m, and a 3 kg mass is at x = 2 m, y = 0 m. The x- and y-coordinates, respectively, of the center of mass of this system are hw5_a2kgmass.gif 1 m, 1 m 2/5 m, 2/5 m 0 m, 0 m 2m, 2 m 6/5 m, 4/5 m

15 s

A Boeing 737 jet plane lands with a speed of 60 m/s (about 135 mi/h) and can decelerate on a wet runway at a maximum rate of 4 m/s2 as it comes to rest. What is the minimum time needed before the plane will come to rest? 12 s 2.25 s 15 s 35 s 4 s

B

A ball is fired by a cannon from the top of a cliff as shown in the figure below. Which of the path would the cannonball most closely follow? test1i2.gif C B A D E

(i) 8, (ii) 3, (iii) 2

A ball is launched up a ramp by a spring as shown in the figure. At the time when the clock starts, the ball is near the bottom of the ramp and rolling up the ramp as shown. It goes to the top and then rolls back down. For the graphs shown below, the horizontal axis represents the time. The vertical axis is unspecified. Select the number of the graph that could correctly represent (i) the x-component of the ball's position, (ii) the x-component of the ball's velocity, (iii) the x-component of the ball's acceleration. Image8.gif (i) 8, (ii) 3, (iii) 2 (i) 1, (ii) 3, (iii) 6 (i) 4, (ii) 4, (iii) 6 (i) 1, (ii) 7, (iii) 2 (i) 8, (ii) 4, (iii) 3

3. 9.8 m/s2, downward

A ball is thrown horizontally from the roof of a 25 m tall building with a speed of 20 m/s. What is its acceleration just before it hits the ground? 1. 0 2. 25 m/s 2, horizontal 3. 9.8 m/s2, downward 4.greater than 9.8 m/s2 to the right and downward.

On the way up, kinetic energy is converted to potential energy.

A ball is thrown straight upward. It rises in the air and then falls back to earth. Neglect friction. It loses mechanical energy as it rises and gains it back as it falls. On the way up, kinetic energy is converted to potential energy. Its total energy is largest at maximum height. It loses energy throughout its motion. None of the above.

(C)

A ball is thrown vertically upward, and as it comes down, it is caught at its initial position. Which of the following graphs best represents the velocity of the ball as a function of time? Image1.gif None of the graphs represents the velocity as a function of time. (A) (B) (D) (C)

(a) constant (b) constant (c) decreasing

A block slides on a track from A to B to C to D. The section from A to B to C is frictionless, but for the section from C to D the coefficient of friction is not zero. Is the block's mechanical (ordered) energy increasing, decreasing, or constant in (a) region AB, (b) region BC, and (c) region CD? h4_blockslides.gif (a) increasing (b) decreasing (c) decreasing (a) increasing (b) decreasing (c) constant (a) constant (b) constant (c) constant (a) constant (b) constant (c) decreasing

The normal force and the gravitational force are equal in magnitude and opposite in direction.

A box is at rest on a flat table. Which of the following is true? Gravity exerts a force on the box that depends on how big the normal or support force is. The normal force and the gravitational force are equal in magnitude and opposite in direction. The normal force and the gravitational force are an action-reaction pair. The magnitude of normal force depends on the coefficient of static friction between the book and the table.

0

A boy holds a 40 N weight at arm's length for 10 s. His arm is 1.5 m above the ground. The work done by the force of the boy on the weight while he is holding it is 0. 60 J. 4 J. 6 J. 90 J.

kinetic energy increases, potential energy decreases

A bungee jumper jumps from a bridge. Describe what happens to the jumper's kinetic and (gravitational and elastic) potential energy right after the jumper has reached the bottom of his descent and is pulled back up? kinetic energy decreases, potential energy increases kinetic energy stays the same, potential energy increases kinetic energy increases, potential energy decreases kinetic energy increases, potential energy stays the same kinetic energy increases, potential energy increases

C.1.5 m/s2

A car has a maximum acceleration of 4.5 m/s2. What would be its maximum accelerationwhile towing a second car twiceits mass? A.2.25 m/s2 B.2 m/s2 C.1.5 m/s2 D.1 m/s2 E.0.5 m/s2

It will increase by a factor of 9

A car's speed changes from 20 mph to 60 mph. By what factor does its kinetic energy change? It will increase by a factor of 9. It will increase by a factor of 6. It will stay constant. It will increase by a factor of 3. There is no way to tell.

(i) E, (ii) A, (iii) B, (iv) G

A cart can move to the right or left along a horizontal track (the positive part of the x axis) as shown in the figure below. Neglect friction. A force is applied to the cart. Choose an appropriate force versus time graph for each statement below. (i) The cart moves toward the right (away from the origin) with constant velocity. (ii) The cart moves toward the right and is speeding up at a steady rate (constant acceleration). (iii) The cart moves toward the left and is speeding up at a steady rate (constant acceleration). (iv) The cart moves toward the right, speeds up and then slows down. h2_cart.gif (i) A, (ii) C, (iii) D, (iv) F (i) A, (ii) C, (iii) D, (iv) G) (i) E, (ii) A, (iii) B, (iv) F (i) C, (ii) A, (iii) D, (iv) G (i) E, (ii) A, (iii) B, (iv) G

Lift: 910N, Fall: 0 N

A clever physics student is able to sneak a scale on a popular ride at an amusement park. Before the ride begins to move, the scale reads 700 N for the student's weight. As the ride lifts, it initially accelerates upward at 3 m/s2. At the top, the riders are held in suspense before the gondola is allowed to free fall downward with acceleration equal to g. What should the scale read for the student's apparent weight during the lift and the fall? Lift: 2100 N, Fall: 700 N Lift: 490 N, Fall: 1400 N Lift: 910N, Fall: 0 N Lift: 490 N, Fall: 0 N Lift: 910 N, Fall: 700 N ****apparent weight in red********

B.The object now accelerates with a=1 m/s2in the positive x-direction

A force of 20 N in the positive x-direction accelerates an object with acceleration a = 2 m/s2. When the object is moving with velocity v = 10 m/s, an additional force of 10 Nin the negative x-directionis applied.Which statement is true? A.The object now accelerates with a= -1m/s2in the negative x-direction B.The object now accelerates with a=1 m/s2in the positive x-direction C.The object now moves with constant velocity D.The object slows down and comes to a stop

The object now accelerates with acceleration a = 1 m/s2 in the positive x‐direction.

A force of 20 N in the positive x‐direction accelerates an object giving it a = 2 m/s2. When the object is moving with velocity v = 10 m/s, an additional force of 10 N in the negative x‐direction is applied. Which statement is true? The object now accelerates with acceleration a = ‐1 m/s2 in the negative x‐direction. The object now accelerates with acceleration a = 1 m/s2 in the positive x‐direction. The object now moves with constant velocity. The object slows down and comes to a stop.

30 W

A girl pulling a sled exerts a 20 N force horizontally for 40 s. How much power does she generate while moving the sled 60 m? Image9.gif 60 W 120 W 30 W 20 W 40 W

The mass M moves in the direction III.

A mass M, attached to a piece of string OM, is whirled round over a person's head in a horizontal circle. At the position shown in the diagram below, the string suddenly breaks. In which direction does the mass M move horizontally after the string breaks? more1_a_mass_M.gif The mass M moves in the direction I. The mass M moves in the direction II. The mass M moves in the direction III. The mass M moves in the direction IV.

½mv2 + ½ky2 + mg(L - y) = mgL

A mass m is lowered gently onto a vertical spring of length L with spring constant k until it just touches the spring. Let y be the distance the spring is compressed and v be the velocity of the mass. The mass is released from rest. Which of the following is the equation for conservation of energy? h4_massm.gif ½mv2 + ½ky2 + mgy = mgL ½mv2 + ½ky2 + mg(L - y) = mgL ½mv2 + ½k(L - y) 2 + mg(L - y) = mgL ½mv2 + ½k(L - y) 2 + mgy = mgL ½mv2 + ½ky2 + mgy = 0

A

A particle is moving with constant speed along the circular path shown. Its velocity vector is shown at two different positions. What is the direction of the acceleration when the particle is at point X? Image3.gif D C A B None of the directions show,.

4.8 m/s

A person walks first at a constant speed of 6 m/s along a straight line from point A to point B and then back along the line from B to A at a constant speed of 4 m/s. What is her average speed over the entire trip? Hint: Assume the distance between A and B is d. How much distance does the person cover on her trip? How long does it take her to cover this distance? 0 5 m/s 3.75 m/s 4,25 m/s 4.8 m/s

F. 20 m

A person walks from A to B along a circular path of radius 10.0 m around 1/2 of the circle. What is the magnitude (in m) of the displacement vector? A. 0 m B. 62.8 m C. 10 m D. 5 m E. 31.4 m F. 20 m

3. 0.45 s

A rock is dropped from a height of 30 m above the ground. How long does it take the rock to fall the last 10 m before it hits the ground?Let g = 10 m/s2. 1. 2.5 s 2. 1.44 s 3. 0.45 s 4. 6 s 5. 2 s

The KE decreases and the PE increases.

A rock is thrown straight up from the surface of the Earth. Which one of the following statements describes the energy transformation of the rock as it rises? Neglect air resistance. Both the KE and the PE of the rock remain the same. The KE increases and the PE decreases. The KE decreases and the PE increases. Both the PE and the total energy of the rock increase. The total energy of the rock increases.

B.9.8 m/s2

A rock is thrown vertically into the air. At the very top of its trajectory, its velocity is momentarily zero. What is its acceleration at this point? A.Zero B.9.8 m/s2 C.Greater than 0 but less than 9.8 m/s2

C.Equal to its weight

A rock is thrown vertically into the air. At the very top of its trajectory, its velocity is momentarily zero. What is the net force on the rock? A.Less than its weight B.More than its weight C.Equal to its weight

D

A small metal cylinder rests on a circular turntable, rotating at a constant speed, as illustrated in the diagram above. Which of the sets of vectors best describes the velocity, acceleration, and net force acting on the cylinder at the position indicated in the diagram? a3_small_metalcylinder.gif A B C D E

It speeds up because of an almost constant force of gravity acting upon it.

A stone is dropped from the roof of a single story building to the surface of the earth. It reaches its maximum speed very soon after it is released. It falls because of the combined effect of gravity pushing it downward and the air pushing it downward. It speeds up because of an almost constant force of gravity acting upon it. It falls because of a natural tendency of objects to rest on the surface of the earth. It speeds up because the gravitational force gets stronger closer to the earth.

(i) B, (ii) D, (iii) E

A toy car is moving on a straight track along the positive x-axis. It stays to the right of the origin. For the situations described below, choose the letter of the correct acceleration vs. time graphs that corresponds to the motion described. (i) The car speeds up at a constant rate, moving away from the origin. (ii) The car slows down at a constant rate, moving away from the origin. (iii) The car moves at a constant speed toward the origin. Image2.gif (i) B (ii) D, (iii) F (i) A, (ii) E, (iii) C (i) A, (ii) D, (iii) F (i) B, (ii) D, (iii) E (i) A, (ii) B, (iii) C

with constantly increasing speed.

A woman exerts a constant horizontal force on a large box. As a result, the box moves across a horizontal floor at a constant speed v0. If the woman doubles the constant horizontal force that she exerts on the box, and the force resisting the motion of the box does not change, the box then moves b2.gif with a constant speed that is greater than the speed v0, but not necessarily twice as great. for a while with increasing speed, then with decreasing speed. with constant speed, that is double the speed v0. for a while with a speed that is constant and greater than the speed v0, then with a speed that increases thereafter. with constantly increasing speed.

The work done on the object by gravity is zero

A woman pulls a crate up a rough, inclined plane at constant speed. Which one of the following statements concerning this situation is false? The gravitational potential energy of the crate is increasing. The net work done by all the forces is zero. The work done on the crate by the normal force is zero. The woman does "positive" work in pulling the crate. The work done on the object by gravity is zero.

the force the mattress exerts on you to stop your descend is much less than the force the sand heap would exert on you

After clearing the bar on a high jump, you land softly on a giant mattress. Landing on a mattress is more comfortable than landing on a sand heap of equal size because the force the mattress exerts on you to stop your descend is much less than the force the sand heap would exert on you. your velocity is less as you land on the mattress than it would be if you landed on the sand heap. you transfer less energy to the mattress in coming to a stop than you would have transferred to the sand heap. you transfer more momentum to the mattress in coming to a stop than you would have transferred to the sand heap. you transfer less momentum to the mattress in coming to a stop than you would have transferred to the sand heap.

1N

An apple at rest weighs 1 N. Now assume the same apple is in free fall near the surface of Earth. Neglect friction. The net force on the apple while it is in free fall is 0. 0.1 N. 1 N. 9.8 N. 10 N.

the upward force by the cable is equal to the downward force of gravity.

An elevator is being lifted up an elevator shaft at a constant speed by a steel cable as shown in the figure above. All frictional effects are negligible. In this situation, forces on the elevator are such that elevator.gif the upward force by the cable is greater than the downward force of gravity. the upward force by the cable is greater than the sum of the downward force of gravity and a downward force due to the air. none of the above. The elevator goes up because the cable is being shortened, not because an upward force is exerted on the elevator by the cable. the upward force by the cable is equal to the downward force of gravity. the upward force by the cable is smaller than the downward force of gravity.

the velocity is zero and the acceleration is equal to g pointing down.

An object is thrown straight up. At the top of its path the velocity is zero and the acceleration is zero. the velocity is zero and the acceleration is equal to the weight. the velocity is zero and the acceleration is equal to g pointing down. the velocity is down and the acceleration is equal to g pointing down. the velocity is up and the acceleration is zero.

0.72 s

Another scheme to catch the roadrunner has failed and a safe falls from rest from the top of a 30.0 m high cliff toward Wile E. Coyote, who is standing at the base. Wile first notices the safe after it has fallen 15 m. How long does he have to get out of the way? h1_coyote.gif 3.06 s 1.74 s 2.47 s 0.72 s 6.12 s

10 microJoule

As a bacterium swims through water it propels itself with its flagella so as to overcome the frictional drag forces and move at, more or less, constant velocity of 100 micrometer/s for periods of time. If the frictional drag force on a bacterium is 0.1 N, how much work does the bacterium do in 1 s? h4_bacterium.gif 10 microJoule 100 microJoule 100 milliJoule 1 J 1 milliJoule

1.6 s

Assume g = 10 m/s2.A gymnast jumps upward with an initial speed of 8m/s. She is in the air for a total time of 1. 1.6 s 2. 2 s 3. 4 s 4. 0.8 s 5. 1.2 s

The average speed is 100 km/hr and the average velocity is zero.

Assume there is a completely straight highway from city A to city B, which is 200 km long. You drive along the highway from A to B and back to A in 4 hours. What are the average speed and average velocity of that trip? The average speed and the average velocity are both zero. The average speed is 100 km/hr and the average velocity is zero. The average speed is zero and the average velocity is 100 km/hr. The average speed and average velocity are both 100 km/hr.

B.+5 ft

Below is shown a straight track along which a toy train can move. If the train moves from point B back to point A and then to point C, what is its resulting displacement? A.-3ft B.+5 ft C.+9 ft D.+11 ft E.+3ft

Yes, this is possible, and a rock thrown straight up is an example.

Can an object's velocity change direction when its acceleration is constant? No, this is not possible because it is always speeding up. No, this is not possible because it is always speeding up or always slowing down, but it can never turn around. Yes, this is possible, and a rock thrown straight up is an example. Yes, this is possible, and a car that starts from rest, speeds up, slows to a stop, and then backs up is an example. Yes, this is possible, but then the net force must change direction.

Car 1

Car 1 starts from rest along a straight highway with constant acceleration a = 1 m/s2. Car 2 passes car 1 with constant velocity of 120 km/hr. Which car is acted on by a larger net force? Car 1 Car 2 Both cars are acted on by the same non-zero net force. The net force on both cars is zero.

I, II, IV and V only.

Consider the following five graphs (note the axes carefully). Which of these represent(s) one-dimensional motion at constant acceleration, including a = 0? Image2_consider_h1.gif All of them I, II and III only. I and II only. V only. I, II, IV and V only.

2. (i) B, (ii) A

Four different mice (labeled A, B, C, and D) ran the triangular maze shown below. They started in the lower left corner and followed the paths of the arrows. The times they took are shown below each figure, (i) Which mouse had the greatest average speed?(ii) Which mouse had the greatest average velocity? 1. (i) D, (ii) C 2. (i) B, (ii) A 3. (i) A, (ii) D 4. (i) B, (ii) C

The net force acting on it is zero.

In an inertial frame, an object cannot remain at rest unless which of the following holds? The net force acting on it is zero. There are no forces at all acting on it. The net force acting on it is constant. There is only one force acting on it.

1

In how many of the following situations does the car have a westward acceleration? -- The car travels westward at constant speed. -- The car travels eastward and speeds up. -- The car travels westward and slows down. -- The car travels eastward and slows down. -- The car starts from rest and moves toward the east. 1 2 3 4 5

exert a force and move in the direction of the force.

In order to do a positive amount of work you must exert a force and move in the direction of the force. exert a force and just move. exert a force or move. change an object's position.

mg.

In the absence of air resistance, a ball of mass m is tossed upward to reach a height of 20 m. At the 15 m position, 3/4 of the way up, the net force on the ball is zero, since there is no resistance. (3/4)mg. (1/4)mg. mg. undefined.

None of the above

Is it possible to have motion in the absence of a force? No. Only in a non-inertial frame. Only in outer space. Only in a moving frame. None of the above

they act on different bodies.

Newton's 3rd law is also called the law of action and reaction. The "reaction" force does not cancel the "action" force because the action force is greater than the reaction force. they are in the same direction. the reaction force exists only after the action force is removed. the reaction force is greater than the action force. they act on different bodies.

~10 N

Refer to the diagram below. Blocks I and II, each with a mass of 1 kg, are hung from the ceiling of an elevator by ropes 1 and 2. What is the force exerted by rope 1 on block I when the elevator is travelling upward at a constant speed of 2.0 m/s? a3_blocks.gif ~2 N ~10 N ~12 N ~20 N ~22 N

pushing against the exhaust.

Rockets receive their forward propulsion through small aerodynamic forces. turbojet engines. pushing against the exhaust. mass conservation of the rocket and fuel. pushing against the ground and objects in space.

A.Greater than your weight

Suppose you are standing on a bathroom scale when you are flying in a jet airplane (you're caught in a physics nightmare) For a moment the scale reads more than your actual weight. During that moment, the scale is exerting an upward force on you that is A.Greater than your weight B.Equal than your weight C.Less than your weight D.Zero

A.-1.1 m/s2

Suppose you are standing on a bathroom scale while riding in an elevator (this is even worse). For a moment the scale reads 160 lb= 712 N while your actual weight is 180 lb= 800 N. What is your (and the elevator's) acceleration? (Let g = 10 m/s2.) A.-1.1 m/s2 B.-1.39 m/s2 C.-10 m/s2 D.-7.1 m/s2 E.-88 m/s

25 m

Suppose you do 1000 J of work on a 4 kg object, and all the work goes into lifting it above the ground. How high above the ground will the object be when all the work has been done? 250 m 100 m 25 m 500 m 1000 m

~0.6

The graph shows the acceleration of a cart with mass m = 0.555 kg, moving initially with constant speed, as a function of time, as a force F = ma stops the cart. Estimate the initial momentum of the cart in units of kgm/s. h5_thegraphshows.gif ~2 ~10 ~0.6 ~21 ~5

U-V

The graph shows the net force acting on an astronaut during a rocket launch into a stable orbit. During which time interval was the acceleration of the rocket the greatest? more1_TheGraphShows.jpg S-T T-U U-V V-W It was the same throughout the launch.

7.1 N.

The magnitude of the force vector with (x, y) components (5 N, 5 N) is zero. 5 N. 10 N. 7.1 N. 8.3 N.

2.99*10-26

The mass of atoms is often given in atomic mass units (u). (1 u = 1.66*10-27 kg) The mass of a hydrogen atom is 1 u, the mass of a carbon atom is 12 u, and the mass of a oxygen atom is 16 u. Calculate the mass, in kg, of a water molecule, H2O. 17 18 2.99*10-26 7.3*10-26 44*10-27

2.99*10-26

The mass of atoms is often given in atomic mass units (u). (1 u = 1.66*10-27 kg) The mass of a hydrogen atom is 1 u, the mass of a carbon atom is 12 u, and the mass of a oxygen atom is 16 u. Calculate the mass, in kg, of a water molecule, H2O. 2.99*10-26 7.3*10-26 17 18 44*10-27

Only the upper block is accelerating.

The positions of two blocks at successive 0.20-second time intervals are represented by the numbered squares in the figure below. The blocks are moving towards the right. Are the blocks accelerating? more1_the_positions.gif No Yes, both blocks are accelerating. Only the upper block is accelerating. Only the lower block is accelerating.

D.The acceleration of a equals the acceleration of b. Both are zero.

The positions of two blocks at successive 0.20-second time intervals are represented by the numbered squares in the figure below. The blocks are moving towards the right. The accelerations of the blocks are related as follows: A.The acceleration of a is greater than the acceleration of b. B.The acceleration of a equals the acceleration of b. Both accelerations are greater than zero C.The acceleration of b is greater than the acceleration of a. D.The acceleration of a equals the acceleration of b. Both are zero. E.Not enough information is given to answer the question

Object 2 with mass m2.

Two moving objects have masses m1 and m2, respectively. If m2 = 4m1, and both have the same kinetic energy, which has more momentum? No relationship between kinetic energy and momentum exists. Object 2 with mass m2. Object 1 with mass m1. Both objects have the same momentum.

four times the orbit for object B.

Two objects are traveling around different circular orbits with constant speed. They both have the same centripetal acceleration, but object A is traveling twice as fast as object B. The orbit radius for object A is one-fourth the orbit for object B. one-half the orbit for object B. the same as the orbit for object B. twice the orbit for object B. four times the orbit for object B.

E.20 N, 10 N

Two objects each accelerate at 2.0 m/s2. The first object's mass is 10.0 kg and the second object's mass is 5.0 kg. What is the magnitude of the force on each object?Hint: Use Newton's second law. A.20 N, 20 N B.10 N, 10 N C.10 N, 5 N D.2 N, 2 N E.20 N, 10 N

Ball B his the ground before ball A.

Two pitchers are standing side by side, and simultaneously throw baseballs A and B. The balls follow the parabolic trajectories shown. Which of the following statements is true? a3_twopitchers.gif Ball A hits the ground before ball B. Ball B his the ground before ball A. Since ball B travels farther, it must have higher initial speed v0. Since ball A reaches a greater height, it must have higher initial kinetic energy.

5000 W

Use g = 10 m/s2. A crane lifts a 200 kg object to a height of 20 m in 8 s. What is its power output? 40000 J 50 W 250 W 5000 W 4000 J

2 MJ

Use g = 10 m/s2. Water descends from the top of a tall hydroelectric dam. Its gravitational potential energy is eventually converted into electric energy. How much gravitational potential energy is released when 1000 kg of water descend 200 m to the generators? 2 MJ 2*106 W 200 KJ 50 J 10 KW

D.None of the above

Velocity vs time graphs are shown for 4 objects, A, B, C, and D. Which statement is TRUE? A.Sometime between t=16 and 17 s, the objects have the same acceleration B.Object A is at rest C.All objects are moving with constant velocity D.None of the above

D. 3.61, θ = 326 deg

What is the magnitude and direction of the vector C= A+ B? A. 13, θ = 238 deg B. 5,θ = 58 deg C. 2.23, θ = 297 deg D. 3.61, θ = 326 deg E. 2.83, θ = 34 deg

The magnitude of the force of static friction is always proportional to the external applied force.

Which of the following observations about the frictional force is incorrect? The magnitude of the force of kinetic friction is always proportional to the normal force. The magnitude of the force of static friction is always proportional to the normal force. The magnitude of the force of static friction is always proportional to the external applied force. The direction of the force of kinetic friction is always opposite to the direction of the relative motion of the object with respect to the contact surface. The direction of the force of static friction is always opposite to the direction of the impending motion of the object with respect to the contact surface. All of the above statements are correct!

Only statements 2 and 3 are true

Which of the following statements about distance and/or displacement are TRUE? (1) Distance is a vector quantity and displacement is a scalar quantity. (2) If a person walks in a straight line and never changes direction, then the distance and the magnitude of the displacement are exactly the same. (3) The diagram below depicts the path of a person walking from position A to B back to C to and then to D. The distance traveled is 90 yds. (4) For the same diagram below, the displacement of the person walking from A to B to C to D is 50 yds. which_following_h1.gif All statements are true Only statements 2, 3, and 4 are true. Only statements 2 and 3 are true. Only statements 3 and 4 are true. Only statements 2 and 4 are true.

A vector quantity has a direction and a scalar does not.

Which of the following statements about vectors and scalars are TRUE? A vector is a large quantity and a scalar is a small quantity. A scalar quantity has a magnitude and a vector quantity does not. The quantity 20 m/s, north is a speed and as such is a scalar quantity. The quantity 9.8 m/s/s is an acceleration value and as such is a vector quantity. A vector quantity has a direction and a scalar does not.

1.A only

Which of the position versus time graphs represents motion with constant positive acceleration? 1.A only 2.B only 3.C only 4.All of them 5.None of them

5

Which position versus time graph does NOT represent motion with constant acceleration? more1_whichposition.gif 1 2 3 4 5

They store energy through compression, like a spring.

Why do elastic balls bounce so well? They are always thrown well. They are all filled with a special energy-absorbent liquid. They store energy through compression, like a spring. They get energy from the floor. They permanently deform, storing energy.

When pushing it away from you and when pulling it towards you.

You are cutting wood with a hand saw. You have to push the saw away from you as it moves away from you and pull it towards you as it moves towards you. When are you doing positive work on the saw? You are not doing work on the saw, the saw is doing work for you. Only when pushing it away from you. When pushing it away from you and when pulling it towards you. Only when pulling it towards you.

Both objects have the same acceleration

You drop an object from a bridge and simultaneously, you throw a-other object downwards at 10 m/s. As the objects are falling, which object has the larger acceleration? (Ignore air resistance.) The dropped object. The thrown object. Both objects have the same acceleration. It depends on the masses of the objects.

During the third meter.

You have watched one too many old cartoons and decide to drive around town with a giant spring that is 4 m long and attached to the front of your car. You decide to help a semi truck that is stuck and try to push them with your car. You take a running start, and when you contact the truck the spring in your car compresses 3 m. During which portion of the compression did you do the most work on the spring? During the first meter During the second meter. During the third meter. The work done is equal for all segments. No work was done on the spring.

432000 J

You operate a 120 W light bulb for 1 hour. How much energy did you use? (1 W = 1 J/s) 120 J 3600 J 432000 J 3.6 MJ 3600 kWh

in the forward direction, towards the front of the boat.

You paddle in a Kayak across a calm mountain lake. Each time you pull the paddle backward through the water, from the front of the boat to its rear, the water exerts a force on the paddle that is in the backwards direction, towards the rear of the boat. sideways, away from the boat. sideways, towards the boat. in the forward direction, towards the front of the boat.

D.The accelerating bus is not an inertial reference frame

You put your book on the bus seat next to you while the bus is parked at the bus stop. When the bus begins to quickly move away from the bus stop, the book slides towards the back of the seat, without anything pushing it. Why? A.The back of the seat and the book attract each other B.The gravitational force pulls the book backward C.The motor produces a strong magnetic field D.The accelerating bus is not an inertial reference frame

3 m/s

You walk in a given direction for 10 m during the first 3 seconds of a trip and then 20 m during the next 7 seconds. Your average speed is equal to 15 m/s. 6.2 m/s. 2.9 m/s. 4 m/s. 3 m/s.

his mass is still essentially unchanged but his weight is less than on earth.

Your class is rather unhappy with the instructor, and they pitch in and decide to fund a sabbatical for him to go to Mars. Unbeknownst to the students the following semester, the instructor has made long distance course arrangements so the "show can go on". The instructor begins talking about mass, weight and related things. He correctly makes which following statement: his mass is still essentially unchanged but his weight is less than on earth. his weight is still essentially unchanged but his mass is less than on earth. his weight and mass have both decreased significantly. his weight and mass have both increased significantly. neither his weight nor his mass have changed much.

the box pushing backward against your hands

Your hands push on a heavy box to slide it across the floor with constant velocity. The other force of the action/reaction pair is friction pushing backward on the box to make the net force on the box zero. gravity pulling downward on the box. friction pushing backward on the floor. the box pushing backward against your hands. the normal force pushing up on the box.