Physics Midterm
A 1000 kg railroad car is moving with a speed of 2 m/s and a 2000 kg load falls in it. What's the new speed?
0.67 m/s
A butterfly moves with a speed of 10 m/s. The x component of its velocity is 9 m/s. The angle between the direction of its motion and the x axis must be
26°
A car travels 20 km West, the 20 km South. What is the magnitude of its displacement?
28.3 km
The statement by Newton that "for every action there is an opposite but equal reaction" is Newton's
3rd Law
A 10 kg mass is moving with a speed of 4 m/s. How much work is required to stop the mass?
80 J
If 10 g of water at 0 C turn to ice at 0 C, the amount of heat released is
800 cal
A pilot drops a bomb. When the bomb hits the ground, the location of the plane is
Above the bomb
A 70 kg man is standing on a 20 kg boat. The man steps to the right thinking he is stepping onto the dock, but what actually happens is
Boat moves left
For a periodic process, the number of cycles per unit time is called the
Frequency
The total mechanical energy of a system
Is constant, only if conservative forces act
The absolute temperature of an ideal gas is directly proportional to its
KE
The coefficient of kinetic friction is ____________ than static friction
Less than
A mass on a spring undergoes SHM. When then mass is at maximum displacement from equilibrium, its instantaneous acceleration
Max
A sample of an ideal gas is slowly compressed to one half its original volume with no change in temperature. What happens to the average speed of the molecules in the sample?
No change
The frequency of a wave increases. What happens to the speed of the wave
No change
Momentum is conserved in all collisions where no external forces are acting except
No exceptions
In general, the frictional force is
Proportional to the weight
Both pendulum A and B are 3.0 m long. The period of A is T. Pendulum A is twice as heavy as pendulum B. What is the period of Pendulum B?
T
A moderate force will break an egg. One dropped on the road will break while one dropped on the grass usually doesn't because for the egg dropped on the grass
Takes longer (T final)
A force acts on a body that is free to move. If we know the force and the mass, we can find the body's
acceleration
In an elastic collision, if the momentum is conserved, then what is true about kinetic energy?
conserved
A container holds N molecules of an ideal gas at a given temperature. If the number of molecules in the container is increased to 2N with no change in temperature or volume, the pressure in the container
x 2
A 0.200 kg mass attached to the end of a spring causes it to stretch 5.0 cm. If another 0.200 kg mass is added to the spring, the potential energy of the spring will be
x 4
Doubling only the amplitude of a vibrating mass and spring system produces what effect on the systems mechanical energy?
x 4
Two vectors A and B have components (0,1) and (-1,3). What are the components of the resultant?
(-1,4)
You throw a ball straight up. Compare the sign of the work done by gravity whole the ball goes up with the sign of the work done by gravity while it goes down.
- to +
You lift a 10 N physics book up in the air a distance of 1 m, at a constant velocity of 0.50 m/s. What is the work done by the weight of the book?
-10 J
A40 N box is pulled 5 m up along a 30 degree inclined plane. What is the work done by the weight (gravitational force) of the box?
-100 J
A force of +10 N accelerates an 8 kg mass at 1 m/s^2. What is the frictional force on the mass?
-2 N
A horizontal force of +10N accelerates an 8 kg mass at a rate of +1 m/s^2. What is the retarding force acting on the 8kg mass?
-2 N
A horizontal force of 5N accelerates a 4 kg mass, from rest, at a rate 0.50 m/s^2 in the positive direction. What friction force acts on the mass?
-3N
Vector A has magnitude 8m at an angle of 30 degrees below the x axis. The y component of A is
-4m
A block is pulled without acceleration across a level surface by a horizontal surface by a horizontal force of 6N. The magnitude of the retarding force on the block is
-6N
A soccerball is kicked with a velocity of 25 m/s at an angle of 45 degrees above the horizontal. What is the vertical component of its acceleration as it travels along its trajectory?
-9.8 m/s
A 3.0 kg object moves to the right at 4.0 m/s. It collides head on with a 6.0 kg object moving to the left at 2.0 m/s. Compare the moments before and after the collision?
0 (initial) = 0 (final)
If you push twice as hard against a stationary brick wall, the amount of work you do
0 J
An apple weighs 1 N. When held at rest above your head, the net force of the apple is
0 N
Four forces, each having a magnitude of 30 N , pull on an object in directions that are 90 degrees apart from each other, the resultant force is
0 N
The coefficient of static and kinetic frictions between a 3kg box and a desk are .40 and .30, respectively. What is the net force on the box when a 10N horizontal force is applied to the box?
0 N
When you sit on a chair, the resultant force on you is
0 N
A ball is thrown with a velocity of 20 m/s at an angle of 60 degrees above the horizontal. What is the vertical component of its instantaneous velocity at the exact top of its trajectory?
0 m/s
Ignoring air resistance, the horizontal component of a projectile's acceleration equals
0 m/s²
An object in simple harmonic motion obeys the following position versus time equation: y= (.50 m) sin (a/2t). What is the amplitude of vibration?
0.05 m
During a hockey game, a puck is given an initial speed of 10 m/s. It slides 50 m on the ice before it stops. What is the coefficient of kinetic friction between the puck on the ice?
0.1
A 10kg box sitting on a horizontal surface is pulled by a 5 N force. A 3 N friction force regards the motion. What is the acceleration of the object?
0.2 m/s^2
A 2 kg mass is attached to the end of a horizontal spring of spring constant 50 N/m and set into simple harmonic motion with an amplitude of .10 m. What is the total mechanical energy of this system?
0.25 J
A 15,000 kg rail car moving at 2 m/s collides and couples with a 50,000 kg car at rest. What is the speed of the cars after the collision?
0.46 m/s
A 70 kg astronaut throws a 2kg space wrench away from him at 17 m/s. How fast will he move?
0.49 m/s
A mass on a spring undergoes SHM. It goes through 8 complete oscillations in 4 s. What is the period?
0.5 s
A 75 kg swimmer dives horizontally off a 500 kg raft. If the divers speed is 4 m/s, what is the raft's speed?
0.6 m/s
The resultant of two vectors is the greatest when the angle between them is
0°
The coefficients of static and kinetic frictions for plastic on wood are .50 and .40 respectively. How much horizontal force would you need to apply to a 3 N plastic calculator to start it moving from rest?
1.5 N
In the Atwood machine shown, if M=0.60 kg and m= 0.40 kg, what is the magnitude of the acceleration of the system?
1.96
A wave moves on a string with wavelength x and frequency f. A second wave on the same string has wavelength 2f. What is the frequency of the second wave?
1/2 f
Two boxes of masses m and 2m are connected by a rope. If the forward force on the big box is F, what is the acceleration of the small box?
1/3 (F/m)
Two boxes of masses m and 2m are connected by a rope. If the forward force on the big box is F, what is the tension in the connecting rope?
1/3 F
A projectile of mass m leaves the ground with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise?
10 m
A ball is fired horizontally from a point 500 m above the ground, strikes the ground after traveling horizontally a distance of 100 m. With what speed was it fired?
10 m/s
A ball is thrown with a velocity of 20 m/s at an angle of 60 degrees above the horizontal. What is the horizontal component of its instantaneous velocity at the exact top of its trajectory?
10 m/s
What is the mass of an object that weighs 100 N on the earth?
10.2 kg
An ideal gas occupies 250 L at an absolute pressure of 300 kPA. Find the absolute pressure if the volume changes to 750 L and the temperature remains constant.
100 kPa
A ball has a velocity of 25 m/s at an angle of 60 above the horizontal, what is its horizontal component?
12.5 m/s
A 0.2 kg tennis ball moving at 12 m/s is struck by a racket and rebounds in the opposite direction at 18 m/s. if the ball and racket are in contact for .05 s, what is the average force exerted on the ball?
120 N
How many kilocalories are needed to heat 750 g of water from 35 C to 55 C?
15 kcal
A wagon weighing 300 N is accelerated on a level surface at 0.5 m/s^2. The net force on the wagon is
15.3 N
A string, fixed at both ends, vibrates at a frequency of 12 Hz with a standing transverse wave pattern containing 3 loops. What frequency is needed if the standing wave pattern is to connect 4 loops?
16 Hz
Ice has a latent heat of fusion of 80 kcal/kg. How much work is required to melt 200 g of ice?
16 kcal
An arrow of mass 20 g, is shot horizontally into a bale of hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force acting on the arrow?
180 N
The resultant of two vectors is the smallest when the angle between them is
180°
A roller coaster starts from rest at point 45 m above the bottom of the dip. Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 25 m above the bottom of the dip?
19.8 m/s
A 5.00 kg object is moved from a height 3 m above the floor to a height 7 m above the floor. What is the change in gravitational potential energy?
196 J
Which of Newton's laws best explains why a motorist should buckle up?
1st Law
The number of forces acting on a car parked on a hill (with parking brakes released) is
2
A 250 kg crate is being pulled across the floor with a horizontal force of 750 N. If the retarding force is 250 N, what is the crate's acceleration?
2 m/s²
A 10 kg box and a 20 kg box are connected by a cable. If the force of the 20 kg box is 60 N, what is the tension in the cable?
20 N
How much heat is required to melt 250 g of ice at 0 C to water at 0 C?
20 kcal or 83.7 kJ
A girl throws a rock horizontally, with a velocity of 10 m/s, from a bridge. It falls 20 m to the water below. How far does the rock travel horizontally before striking the water?
20 m
If it takes 50 m to stop a car initially moving at 25 m/s, what distance is required to stop a car moving at 50 m/s under the same condition?
200 m
A horizontal force of 200 N is applied to move a 55 kg cart (initially at rest) across a 10 m level surface. What is the final kinetic energy of the cart?
2000 J
A car is travelling on a level highway at 15 m/s. A braking force of 3000 N brings the car to a stop in 10s. The mass of the car is
2000 kg
A runner runs halfway around a circular path of radius 10m. What is the displacement of the jogger?
20m
If 40 kcal of heat is added to 2 kg of water, what is the resulting temperature change?
20°C
An object is lifted vertically 2 m and held there. If the object weighs 120 N, how much work was done by in lifting it?
240 J
An elevator of mass 2000 kg is supported by a cable. What is the tension in the cable when the elevator is accelerating upward at 3 m/s^2?
25,600 N
A 60 kg skier starts from rest at the top of a 50 m high slope. If the work done by friction is -6.0x10^3 J, what is the speed of the skier on reaching the bottom of the slope?
28 m/s
What is the spring constant of a spring that stretches 2 cm when a mass of 0.6 kg is suspended from it?
294 N/m
A net force F acts on mass m and produces acceleration a. What acceleration results if force 8F acts on mass 4m?
2a
A mass m hanging on a spring has a natural frequency f. If the mass is increased to 4m, what is the new natural frequency?
2f
Two displacement vectors have magnitudes 5m and 7m. The magnitude of the sum is
2m or 12m
A mass is placed on a smooth inclined plane with an angle of 30 degrees to the horizontal. If the inclined plane is 10 m long, how long does it take the mass to reach the bottom of the inclined plane after it is released from rest?
2s
The number of forces acting on a car parked on a hill (with parking brakes engaged) is
3
A container of an ideal gas at 1 ATM is compressed to one third its plume, with the temperature held constant. What is the final pressure?
3 atm
Two snowballs of mass 0.4 kg and 0.6 kg are thrown and collide head on into a single mass. The magnitude of their initial velocity is 15 m/s for each snowball. What is the speed of the combined 1 kg mass?
3 m/s
A 500 kg elevator is pulled upward with a constant force of 5500 N for a distance of 50 m. What is the net work done on the elevator?
30,000 J
Two vectors, of magnitudes 20 and 50, are added. What is the range of possible magnitudes of the resultant?
30-70
What is the frequency of a wave which has a period of 3.00 ms?
333 Hz
A ball has a velocity of 40 m/s at an angle of 60 above the horizontal, what is its vertical component?
34.6 m/s
What is the velocity of propagation if a wave has a frequency of 12 Hz and a wavelength of 3.0 m?
36 m/s
A spring is characterized by a spring constant of 60 N/m. How much potential energy does it store, when stretched by 1 cm?
3x10⁻³ J
Two vectors A and B have components (0,1) and (-1,3). What is the magnitude of the resultant?
4.1
A 2 kg mass on an 18 N/m spring is displaced slightly from its equilibrium position and released. What is the frequency of vibration?
4.7 Hz
An object is on a frictionless inclined plane. The plane is inclined at an angle of 30 degrees with the horizontal . What is the object's acceleration?
4.9 m/s^2
What is the momentum of a 2000 kg truck traveling at 20 m/s?
40,000 kgm/s
A 12 kg object is moving along on a rough, level surface. It has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. How far will it slide?
48 m
A 10 kg mass, hung onto a spring, causes the spring to stretch 2 cm. What is the spring constant?
4900 N/m
An airplane of mass 1.5 x 10^4 kg tows a glider of mass 0.5 x 10^4 kg. If the airplane produces a thrust of 10 x 10^4 N, what is the acceleration of the glider?
5 m/s²
A 10 N force is needed to move an object with a constant velocity of 5 m/s. What power must be delivered to the object by the force?
50 W
A person stands with two feet on a scale and the scale reads 500 N. If the person lifts up one foot, the scale will read
500 N
Vector A= (1,3) B= (3,0). Vector A+B=C. What is the magnitude of C?
5m
The acceleration of gravity on the moon is only one sixth of that on earth. If you hit a baseball on the moon with the same effort (and at the speed and angle) that you would on earth, the ball would land how much further away?
6 times
The coefficient of static and kinetic frictions between a 3kg box and a desk are .40 and .30, respectively. What is the net force on the box when a 15N horizontal force is applied to the box?
6.2 N
An ideal gas occupies 600 cm^3 at 27 degrees C. At what temperature will it occupy 1200 cm^3 if the pressure remains constant?
600 K
A cyclist does work at the rate of 500 W while riding. How much force does her foot push with when she is travelling at 8 m/s?
62.5 N
Ten grams of mercury change from a liquid to a vapor at its boiling point of 357 C when 706 cap are added. The heat of vaporization of mercury is
70.6 cal/gram
A stone is thrown horizontally with an initial speed of 10 m/s from the edge of a cliff. A stop watch measures the stones trajectory time from the top of the cliff to the bottom to be 4s. What is the height of the cliff?
78.4 m
A 10kg mass slides down a flat hill that makes an angle of 60 degrees with the horizontal. If friction is negligible, what is the resultant force on the sled?
85 N
A small object with a momentum of magnitude 5 kgm/s approaches head on a large object at rest. The small object bounces straight back with a momentum of magnitude 4.0 kgm/s. What is the magnitude of the small objects momentum change?
9 kgm/s
A force of 24 N acts on a mass initially at rest. How long will it take the mass to reach 54 m/s?
9s
A mass is attached to a vertical spring and bobs up and down between points A and B. Where is the mass located when its kinetic energy is a minimum?
A and B
The action and reaction forces referred to in Newton's third law
Act on different bodies
On a plot of force versus position (F vs. x), what represents the work done by the force F?
Area under the curve
The number of molecules in one mole of a substance
Avogadro's Number (6.022 x 10^23)
A rubber ball and a lump of putty have equal mass. They are thrown with equal speed against the wall. The ball bounces back with nearly the same speed with which it hit. The putty sticks to the wall. Which object experiences the greater momentum change?
Ball
Turning up the flame under a pan of boiling water causes it to
Boil faster
Two toy cars (16kg and 2kg) are released simultaneously on an inclined plane that makes an angle of 30 degrees with the horizontal. Which statement best describes their acceleration after being released?
Both cars accelerate at the same right
A gas is expanded to twice its original volume with no change in temperature. This process is
Boyle's Law
A gas is allowed to expand at constant pressure as heat is added to it. This process is
Charles Law
By what primary heat transfer mechanism does one end of an iron bar become hot when the other end is placed in a flame?
Conduction
On a cold day, a piece of metal feels much colder to the touch than a piece of wood. This is due to the difference in which physical property?
Conduction
When a cannon fires a cannonball, the cannon will recoil backwards because the
Conservation of momentum
Ignoring air resistance, the horizontal component of a projectile's velocity is
Constant
A freight car moves along a frictionless level railroad track at constant speed. The car is open on top. A large load of coal is suddenly dumped into the car. What happens to the velocity of the car?
Decreases
An object is sitting on a plane which can be inclined with respect to the horizontal. What happens to the normal force as the angle of inclination increases?
Decreases
A 50,000 N truck collides with a 10,000 N car. The force the truck exerts on the car during the collision is _________ the force the car exerts on the truck.
Equal to
A mass is attached to a vertical spring and bobs up and down between points A and B. Where is the mass located when its kinetic energy is a maximum?
Equilibrium
An example of a force which acts a distance is
Fg
The number of crests of. A wave passing a point per unit time is called the waves
Frequency
An acorn falls from a tree. Compare its kinetic energy KE, to its potential energy GPE.
GPE (initial) = KE (final)
A gas is confined to a rigid container that connote expand as heat energy is added to it. This process is
Gay-Lussac
A cart is being accelerated by a constant force. If suddenly the carts mass is doubled, what happens to the carts acceleration?
Halved
In the absence of a net force, an object will ALWAYS
Have constant velocity
While a body is moving, the forces acting on it vanish. The body will
Have constant velocity
In a cloud formation, water vapor condenses into water droplets which get bigger and bigger until it rains. This will cause the temperature of the air in the clouds to
Increase
The weight of a body
Is the force which attracts it to the earth
The quantity 1/2 mv^2 is
KE
The Newton is equivalent to
Kg m/s²
A rock suspended from a string is accelerated downward. The tension in the string is _____________ the weight of the rock
Less than
A ball drops some distance and loses 30 J of gravitational potential energy. Do not ignore air resistance. How much kinetic energy did the ball gain?
Less than 30 J
One of the forces of an action reaction force pair
May or may not produce a change in velocity
Which of the following operations will not change a vector?
Move it parallel to itself
If you fill a balloon with helium and release it, it will fly away. This is an illustration of
Newton's 2nd Law
Can work be done on a system if there is no motion?
No
Does the centripetal force acting on an object do work on the object?
No
If you double both the pressure and absolute temperature of an ideal gas, the volume of the gas will
Not change
In an inelastic collision, if the momentum is conserved, then what is true about kinetic energy?
Not conserved
The time for one cycle of a periodic process is called the
Period
In seismology, the S wave is a transverse wave. As an S wave travels through the earth, the relative motion between the S wave and the particle is
Perpendicular
The quantity Fd/t is
Power
By what primary heat transfer mechanism does the sun warm the earth?
Radiation
If the sum of the forces on an object is zero, the velocity of the object always
Remains constant
A horse pulls a wagon along a horizontal road. The force that causes the horse to move forward is
Road --> Horse
A 4.0 kg mass is moving with a speed 2 m/s. A 1.0 kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before stopping?
Same
A bullet is fired horizontally, and at the same instant a second bullet is dropped from the same height. Ignore air resistance. Compare. The times of fall of the two bullets.
Same
A mass oscillates on the end of a spring, both on earth and on the moon. Where is the period the greatest?
Same
A mass undergoes SHM with an amplitude of 4 cm. The total energy is 8.0 J. The mass is cut in half , and the system is again set in motion with amplitude 4.0 cm. What is the energy of the system now?
Same
A pin gpong ball gun is fired. Compared to the impulse on the ball, the impulse on the gun is
Same
A small object collides with a large object and sticks. Which object experiences the larger magnitude of momentum change?
Same
Oxygen molecules are 16 times more massive than hydrogen molecules. At a given temperature, the average molecular kinetic energy of oxygen, compared to hydrogen
Same
Who has a greater weight to mass ratio, a person weighing 400N or one weighing 600N?
Same
A cup of water is scooped up from a swimming pool of water. Compare the temperature T and the internal energy U of the water, in both the cup and the swimming pool.
Same T; U of pool is greater
If the acceleration vector of an object is directed opposite to the velocity vector, the object is
Slowing down
An object is placed on an inclined plane. The angle of incline is gradually increased until the object begins to slide. The angle at which this occurs is (theta). What is the coefficient of static friction between the object and the plane?
Tan(θ)
A mole of diatomic oxygen molecules and a mole of diatonic nitrogen molecules at STP have
The same number of molecules
It is a well known fact that water has a higher specific heat capacity than iron. Now, consider equal masses of water and iron that are initially in thermal equilibrium. The same amount of heat, 30 calories, is added to each. Which statement is true?
They are no longer in thermal equilibrium, iron is warmer
Which one of the following is an example of a vector quantity?
Velocity
The temperature of an ideal gas increases from 2C to 4C while remaining at constant pressure. What happens to the volume of the gas?
Very small increase
Of the following , which is not a unit of power?
Watt/second
The area under the curve, on a force versus position (F vs. x) graph represents
Work
Is it possible for a system to have negative potential energy?
Yes
When a mass in SHM is at its maximum displacement from equilibrium, its instantaneous velocity
Zero
If the momentum of an object changes and its mass is constant, what else is happening to the object?
acceleration
In a wave, the maximum displacement of points of the wave from equilibrium is called the waves
amplitude
The reason ocean temperatures do not very drastically is that
c(water)= 4186 J
What is the smallest unit of heat energy?
calorie
Phase change occurs as the temperature
constant
When a vapor condenses, the temperature of the substance
constant
The frequency of a wave increases. What happens to the distance between successive crests?
decreases
The force that keeps you from sliding on an icy sidewalk is
f
A packing crate slides down an inclined ramp at constant velocity. Thus we can deduce that
friction
Which of the following is the correct unit of work expressed in SI units?
kg m^2/s^2
A measure of an objects inertia is given by its
mass
Newton's second law states that the acceleration of an object acted on by a net force is inversely proportional to its
mass
A block of mass M slides down a frictionless plane inclined at an angle (theta) with the horizontal. The normal reaction force exerted by the plane on the block is
mgcos(theta)
The impulse experienced by a body is equivalent to the change in which of the following quantities?
p (momentum)
Which of the following is an example of a scalar quantity?
speed
The cue ball collides with another identical ball at rest in a head on collision. The cue ball
stops
The distances between successive crests on a wave is called the waves
wavelength
A 10 N force and a 20 N force act on an object in opposite directions. The net force on the object is
±10 N
Its more difficult to start moving a heavy carton from rest than it is to keep pushing it with constant velocity, because
µs is greater than µk
The area under the curve of a force versus time (F vs. t) graph represents
∆p (impulse)