Straighter Line Physics

A binary star system consists of two identical stars moving in circular orbits around the system's center of mass (see the diagram). The mass of each star is M and the radius of the orbit is R. Which expression correctly gives the orbital speed for one of the stars?

(GM/4R)1/2

An automobile of mass 900 kg is moving at a speed of 12.5 m/s when it encounters a hill. At the bottom of the hill the car speed increases to 14.6 m/s. If the elevation of the hill is 15.3 m, how much work did the brakes do while going down the hill?

-1.09x105 J

What is the change of entropy for 3.0 kg of water when the 3.0 kg of water is changed to ice at 0oC? (Lf = 3.34 x 105 J/kg)

-3.7 kJ/K

A spaceship is in space and currently at rest. The directive is given to accelerate from rest to a speed of 2.90 × 103 m / s. If the fuel budgeted for this action is 400 kg, which of the following is velocity of the exhaust gas required if the ship mass is 7.38 ×103 kg?

-5.5 × 104 [m / s]

What is the acceleration of a skydiver at terminal velocity whose mass is 80 kg and cross-sectional area is 14 m2. The density of the air he is falling through is 0.9984 g / m3. The drag coefficient has a value of 0.485.

0 m / sec2

In a particle accelerator, two particles collide head-on with each other. Their total masses are 1.67 × 10−27 kg and 9.1 × 10−31 kg. If the less massive one experiences an acceleration of 45 m / s2, what is the acceleration of the other particle?

0.025 m / s2

In a game of marbles, a 60 g marble is rolling at 8.00 cm / s when it collides with a stationary marble. the 60 g marble takes off at a 27° angle at a reduced speed of 4.89 cm / s. The second marble moves at a rate of 3.21 cm / s at a 31.7° angle. Which of the following is the mass of the second marble?

0.0800 kg

A child has only one pea left on her plate. Playing with her food she finds that if she tilts the plate at an angle of 15 degrees or more, the pea starts to slide down. What is the coefficient of static friction between the pea and the plate?

0.27

The equation for torque is given by τ=F×dτ where F is a force applied at a distance d→ from the axis of rotation. Which of the following is the magnitude of torque resulting from a 2.4 N force applied 17 cm from the point of rotation if the force is applied at a 45∘ angle to the displacement vector?

0.29 N⋅m

A juggler is juggling 3 balls. If she throws them 2.4 m in the air at an angle of 80° relative to the horizontal, what is the time between throws? (You should ignore air drag and the time it takes for the juggler to move balls from one hand to the other.)

0.47 s

A car travels with a speed of 3.5 m / s, and then accelerates to 5.5 m / s in 4 s. Which of the following is the average acceleration of the car?

0.5 m / s2

A 200 g plastic ball is at rest on a frictionless incline 0.658 m above the surface of a table. The ball then rolls down the incline and across the table, coming to rest after a distance of 2.45 m. Which of the following the average friction on the ball while rolling across the table.

0.527 N

An empty freight train car of mass 10,000 kg is rolling along a level section of track at 2.00 m / s. It collides with a loaded car of weight 1.96 × 105 N, which is at rest. The cars couple upon collision. Which of the following is the speed of the train after the collision?

0.667 m / s

Consider a rectangle with a base of 0.567 m and a height of 1.606 m. What is its area?

0.911 m2

Match each of the following descriptions of motion with the appropriate graph. resting uniform motion accelerated motion oscillating motion

1-B; 2-D; 3-C; 4-A

A 2.5 kg object is suspended from a spring with a spring constant of 48 N / m. The mass is pulled 0.25 m downward from its equilibrium position and released. Which of the following is the maximum kinetic energy of the object?

1.5 J

Laura is listening to a record spinning at 45 rpm (revolutions per minute). When she switches the speed selector on the record player to 33 rpm, it takes 2.7 seconds for the record player to change to the new speed. How many revolutions does the record make during this time? Assume that the angular acceleration of the record is constant.

1.8

A mass of 5.2 kg is accelerated to 4.0 m / s2 when a force of magnitude F is applied to it. If the same force is applied to another object causes it have an acceleration of 1.8 m / s2, what is the mass of this object?

12 kg

A 1,450 kg car moves with a speed of 25.0 m / s when it collides with a stationary car having a mass of 1,550 kg. The two vehicles lock bumpers on impact. The two cars then collide with a stationary third car of mass 1,250 kg. During this second impact, the third vehicle becomes attached to the second but the first car is breaks free and moves at 0.125 m / s in the opposite direction. Which of the following is the final velocity of the second and third cars after the final collision?

13.01 m / s

A UFO lowers a 268 kg stairway of length 5.29 m from under its belly until it is fully extended at an angle of 54°. The stairway is free to pivot on a hinge and it is supported at its far end by a vertical cable. What is the tension in the cable? Treat the stairway as a uniform rectangular slab.

1310 N

Given the vectors C=1.5i^+6.2j^ and D=4.4i^+7.3j^, calculate the magnitude of their vector product.

16.3

A cart with mass m1 = 24 kg lies on an incline that makes an angle of 17° with the horizontal. The coefficients of static and kinetic friction are 0.7 and 0.5 respectively. The cart is tied by an ideal rope that runs through a frictionless pulley as shown in the diagram. What tension do you need to apply to the free end of the rope in order to make the cart go up the incline at a constant velocity?

181 N

Which of the following is not a vector?

2 kg of mass under a table

The distance between the front and rear wheels of a 2280 kg car is 3.15 m. The car's center of gravity lies in the middle of the car, 1.05 m behind the front wheels. When the car is at rest, what is the ratio of the force exerted by the ground on the front wheels to that exerted on the rear wheels?

2.0

Tom and Joe are trying to fly a new style of kite that they have invented. Both of them are holding strings attached to the kite. The tension in each string is 126 N. The angle between the strings is 36°. Unfortunately, the kite will not rise in the air, and the strings held by Tom and Joe are essentially parallel to the ground. Tom and Joe have run a distance of 100 m trying to get the kite to fly. How much work have they done on the kite?

24,000 N • m

A pendulum bob has mass of 0.750 kg and is on a pendulum arm of length 1.00 m. The pendulum is pulled back so that the arm makes an angle of 60.0° from the vertical and is then released. Which of the following is the speed of the mass when it reaches its lowest point?

3.13 m/s

What is correct magnitude of the position vector for the following description of the motion of an object? A car moves 3 blocks west, then 2 blocks north, and then 3 blocks south before stopping briefly. It then moves 1 block east and finally 2 blocks south.

3.6 blocks

A scientific team has designed a thin film that enables them to measure normal forces from surfaces. They lay this thin film on a flat surf

3.6 kg

A steel playground slide is 5.25 m long and is raised 2.75 m on one end. A 45.0 kg child slides down from the top starting at rest. The final speed of the child at the bottom is 6.81 m/s. Find the average force of friction between the child and the slide.

32.2 N

A 0.200 kg dart is fired horizontally at a speed of 2.75 m / s when it hits a 0.700 kg block of wood suspended by a string. The nose of the dart sticks into 0.00210 m the wood. Together the dart and block swing upwards from a height of 0.0500 m above a table to 0.128 m above the table. Which of the following is the average force the dart applies to the block during impact?

32.4 N

A mass-spring system has an amplitude of0.820 m and a period of 0.690 s. If the mass attached is 0.500 kg, what is the acceleration at half the amplitude?

34.0m/s2

A train is on an incline and has a mass of 2.36 × 103 kg. It initially coasts at 27.8 m/s. Which of the following is the speed of the train at position B. Assume no additional assistance from the engine.

34.2 m/s

The driver of a truck is moving at 48 km / hr. A ball rolls out in the street 30 m ahead of him. He applies the brakes. Assuming a constant acceleration, how much time does the driver have before he reaches the ball?

4.5 s

A 2.6 cm × 5.2 cm domino of mass 18 g is set in the position shown and released. Taking the domino to be a uniform rectangle plate, what is its angular acceleration about the corner that rests on the surface? The moment of inertia of a uniform rectangular plate with side lengths a and b about an axis running perpendicular to it and through its center is I=112M(a2+b2)

41rad/s2

If the cross product of a vector of length 5 and a vector of length 3 results in a vector of length 10, what is the angle between them?

42°

If the x-component of a vector is 3 and the y-component is 4, what is the magnitude of the vector?

5

An ordinary glass is filled to the brim with 350 cm3 of water at 100oC. If the temperature decreased to 20oC, how much water could be added to the glass? Neglect the volume expansion of the glass. (β water = 207 x 10-6/Co)

5.80 cm3

A mass of 4.3 kg is accelerated to 6.0 m / s2 when a force of magnitude F is applied to it. If the same force is applied to a mass of 0.5 kg, what is the acceleration of this mass?

51.6 m / s2

Consider a mass of 85 kg lying on the ground. The coefficient of static friction between them is μs=0.65μs=0.65. What is the minimum force you need to apply in order to slide the mass?

541 N

A surveillance plane weighing 1.91 × 104 N is flying horizontally at a velocity of 59.4 m / s due west in thick clouds. Suddenly the plane is struck a glancing blow from another plane. Before impact, this smaller plane weighing 9.74 × 103 N was traveling at 114 m / s due northwest at constant altitude. Immediately after impact, the second plane is knocked of course to a heading of 89.8 m / s at 35.2° north of west. Which of the following is the velocity of the surveillance plane after the collision?

64.8 m / s at 13.1° north of west

A 16 lb bowling ball is resting in an angled crook, as shown. What is the force exerted on the ball by the right-hand surface? 1 Newton is equivalent to 0.225 lb.

68 N

The radius of the Moon is known to be 1.7 × 106 m. Astronauts who walked on the Moon measured the time it takes an object to fall 1 m on the Moon to be about 1.1 s. Using this information, which of the following is the mass of the Moon?

7.1 × 1022 kg

If vector A→ makes an angle of 37∘∘ with the x-axis and has a length Ax=12 what is the length Ay?

9

Exhaust gas from a rocket ship is released at a speed of 1,000 m / s so that the craft accelerates from 100 m / s to 200 m / s. How much fuel is necessary to complete this acceleration if the mass of the ship was originally 10,000 kg?

951.6 kg

Which is the definition of a derived unit?

A unit which is based on other (basic) units.

What is the difference between a vector and a scalar?

A vector has both magnitude and direction; scalars have only magnitude.

Consider a spring that is stretched from its equilibrium position x0, where x0 = 0, to a position x, where x is positive. Which of the following describes why the work done by a spring is negative?

All of the choices are correct.

Why is (vector) A⋅ (vector) B =AxBx+AyBy

All the cross-terms are equal to zero.

Given the vector A→ as shown in the figure, select the choice that gives the vector's correct description in component form.

Ax=Acosθ Ay=Asinθ

Given the vectors A=6i^+3j^ and B=i^+9j^, find their scalar product A→⋅B→

A⋅B=33

Which of the following is a form of Hooke's law, where Fs is a spring force?

Fs = -kx

A 0.500 kg steel ball is dropped from a height of 4.00 m onto a horizontal steel slab. The collision appears elastic in that the ball rebounds to its original height. If the collision lasts for 2.00 × 10−3 s, which of the following is the impulse imparted to the ball and the average force applied to the ball during the collision?

I = 8.85 kg•m / s F = 4.43 × 103 N

Which of the following is the general definition of impulse ?

I =∫t2t1 ΣF→dt

This hourglass-shaped object is hung from a pivot point (round dot). Its center of gravity is marked by a cross. If the object is free to rotate, what does it do?

It does not move.

What would happen to the precession of a gyroscope if there were no gravity?

It would not precess

What would happen to the precession of a gyroscope if it were spinning in the opposite direction?

It would precess in the opposite direction.

Would an object precess faster if it had more angular momentum?

No, because the angular velocity of precession is inversely proportional to the magnitude of the gyroscope's angular momentum

The Ideal Gas law is given by which equation? (n is the number of moles of the gas)

PV = nRT

Why does an ice skater's angular velocity increase when she pulls in her arms during a spin?

She reduces her moment of inertia.

What is the tension in each rope shown in the diagram? The ropes are suspending two equal weights of 40 N.

T1=40N T2=58.5N T3=71.7

Two identical boxes are moved in equal distances in the horizontal direction. Box A experiences a constant net force F applied at an angle θ to the horizontal and box B experiences a constant net force of 2 F applied at an angle of 2 θ to the horizontal. Which of the following is correct?

The amount of work done on each box cannot be determined from the data given.

A rocket leaves the surface of the Earth and flies to a distance of one Earth radius above the surface of the Earth. What happens to both the gravitational force and potential energy of the rocket?

The force decreases by factor of 4. The potential energy increases by factor of 2.

Which of the following statements concerning friction between the surfaces of two objects is correct?

The force of friction mostly depends on the nature of the two surfaces.

Which of the following statements concerning friction is incorrect?

The force of static friction ( fs ) between parallel surfaces in contact is given by: fs = μsN.

Scientist A and Scientist B are both observing a ball that falls to the ground from a height of 10 m. Scientist A uses coordinate system A to measure the ball's position relative to time as shown in graph A.Scientist B uses coordinate system B to measure the ball's position as it falls.Which of the following graphs represents Scientist B's observations?

The graph curving up

Suppose you are driving a car at a constant speed of 40 mph in a straight line. All of a sudden the road curves to the right but you manage to keep driving at exactly the same speed. Which of the following statements is correct?

There was a net force acting on the car.

Which is not a reason why measurements are important?

They give us an absolute analysis of the world around us.

In the following graph, which point in time is associated with an instantaneous velocity that is closest to zero?

Time C

As shown, a crate of oranges and a crate of apples, each with a different mass, are attached by a rope (with tension Toa). A second rope (To ) is attached to the crate of oranges, and the entire system is pulled with a constant acceleration a by this rope. Which of the following is true of the tensions?

Toa > To

A mass m is dropped from rest to the ground from a height h. Which of the following is correct?

When it strikes the ground the speed of the mass is independent of m.

When a small car pulls a trailer for a move, which of the following explains why the trailer moves?

While the force of the trailer on the car is equal and opposite to the force of the car on the trailer, the total of all forces acting on the car are unbalanced.

A ride at an amusement park begins by spinning patrons about a circle of radius R with constant speed v. At some point during the ride the speed doubles and the spokes extend, quadrupling the radius. After this occurs, what is the acceleration of the patrons in terms of the original acceleration, a ?

a

Which of the following results from (A×B)×C where A,B and C are all vectors? (Assume that none of the cross products results in zero.)

a vector

Two vectors can be added graphically by __________.

adding them tip to tail

A gas is quickly compressed in an isolated cylinder. This process is ________________.

adiabatic

A track athlete runs in a 400 m race, which is once around a track. If the runner ends the race with a time of 52.5 s, which of the following is the average velocity and the average speed of the athlete?

average velocity: 0 average speed: 7.6 m / s

How is a kilogram defined?

by a platinum brick in Europe

When applied to a system, a nonconservative force _____________

cannot generate potential energy with the system.

When applied to a system, a nonconservative force _____________.

cannot generate potential energy with the system.

Which is not an mks unit?

centimeter

Which of the following applies to the tangential velocity v of uniform circular motion?

constant speed but not constant velocity

A large object of mass 2M free to slide on a frictionless surface is connected to a smaller, hanging object of mass M by an ideal string. The string runs over a pulley with moment of inertia I and radius R. If the system starts from rest, how fast are the masses moving after the smaller mass drops by a height h ?

d. √2Mgh/3M+I/R2

A power company charges its customers for electricity based upon which one of the following?

energy

The unit of angular momentum is ___________.

kg⋅m2/skg⋅m2/s

A person with mass m is on a ride in an amusement park. She is accelerated by a vertical wall with an acceleration of a→ and her feet are not touching the floor. Ignoring air resistance, the normal force must be equal to _______________. (Acceleration due to gravity is g→ and t is the angle between the normal force and mg→)

ma→

Consider a mass m that is attached to a rope such that the mass is in uniform circular motion. Which of the following is the magnitude of the centripetal force?

mv 2/r

Which of the following physical quantities can be negative?

potential energy

Which of the following is not a vector quantity?

power

Which is the standard unit of time in the metric system?

second

Which graph best illustrates the following description of motion? A car starts at rest, accelerates at a constant rate until it cruises at a constant speed, and then brakes at a constant rate until it is moving at a constant, very slow speed.

the graph that inclines and then plateaus

Evaluate the following statments as true or false. It is possible for a man who can lift a maximum of only 200 N to hold an object weighting 1000 N above the ground, provided he has access to a lever that is 3 m long as shown in the diagram. The weight of the lever is negligible.

true

A truck weighing 1000 N moves at 5.89 m / s when it has an elastic collision with another vehicle. The second vehicle, weighing 981 N, was stationary but free to move. Which of the following is the final velocity of the first vehicle after the collision?

v1 f = 0.0565 m / s

Three pool balls of equal mass are resting on a horizontal frictionless surface. The cue ball (Ball 1) of mass 700 g is rolled into a stationary pool ball (Ball 2) and rebounds at 1.00 m / s in the direction from which it came. Ball 2 does not move, but it is touching another pool ball (Ball 3), which rolls away at 4.00 m / s. Which of the following is the initial speed of the cue ball, v1i? Also, given that the encounter between the cue ball and cue stick lasts for only 0.0500 s, which of the following is the average force delivered F to the cue ball by the stick?

v1i = 3.00 m / s F = 42.0 N

Which is not a basic unit?

velocity

If the position vector of an object is r→=4t2i^−3j^, what are the instantaneous velocity vector components at t=1s?

vx = 8 m / s, vy = 0 m / s

hich of the following is not a unit of the metric system or Système International?

yard

Given the vectors C=2i^+7j^ and D=14i^+38j^D, find the angle θ between them.

θ=4∘

A 309 g glass rolls down an incline and onto a horizontal platform where it hits a beverage can that is laying at rest on its side. The top of the incline is 11.0 cm above the horizontal platform. The beverage can is initially at rest and weighs 7.35 N. Which of following is the final velocity of the glass?

−0.612 m / s

A boat pulls a water skier who weighs 127 lbs at a constant speed. The tension in the ski rope is 125 N. The skier makes a run that is 0.7 km down a long straight river. What is the work done by the water skier on the boat?

−8.75 × 104 N • m