AP Physics Midterm

A child has a toy tied to the end of a string and whirls the toy at constant speed in a horizontal circular path of radius R. The toy completes each revolution of its motion in a time period T. What is the magnitude of the acceleration of the toy?

(4πr^2) / (T^2)

A block of mass m is accelerated across a rough surface by a force of magnitude F that is exerted at an angle ϴ with the horizontal. The frictional force exerted by the surface has magnitude f. What is the acceleration of the block?

(Fcosϴ - f) / m

Two masses m1 and m2 are connected by a cord and arranged with m1 sliding along on a frictionless surface and m2 hanging from a light frictionless pulley. What would be the mass of the falling mass m2 if both the sliding mass m1 and the tension T in the cord were known?

(Tm1) ________ (gm1-T)

In which of the following situations would an object be accelerated?

- It moves in uniform circular motion - It travels as a projectile in a gravitational field with negligible air resistance

A person stands on a merry go round which is rotating at constant angular speed. Which of the following are true about the frictional force exerted on the person by the merry go round?

- the force is opposite in direction to the frictional force exerted on the person by the merry go round - the force is dependent on the person's mass

A child whirls a ball at the end of a rope, in a uniform circular motion. Which of the following statements is true?

-The speed of the ball is constant -The magnitude of the ball's acceleration is constant

An object has a weight W when it is on the surface of planet with radius R. What will be the gravitational force on the object after it has been moved to a distance of 4R from the center of the planet?

1/16W

Two people are pulling on the ends of a rope. Each person pulls with a force of 100 N. The tension in the rope is

100 N

A system of two wheels fixed to each other is free to rotate about a frictionless axis through the common center of the wheels and perpendicular to the page. Four forces are exerted tangentially to the rims of the wheels. The magnitude of the net torque on the system about the axis is

2FR

A diver initially moving horizontally with speed v dives off the edge of a vertical cliff and lands in the water a distance d from the base of the cliff. How far from the base of the cliff would the diver had landed if the diver initially had been moving horizontally with speed 2v?

2d; d=vt

An object is released from rest and falls a distance h during the first second of time. How far will it fall during the next second of time?

3h

Each of five satellites makes a circular orbit about an object that is much more massive than any of the satellites. The mass and orbital radius of each satellite are given below. Which satellite has the greatest speed?

mass: m radius: 1/2R

Which object moves with constant nonzero acceleration?

neither A or B

Which object is furthest from the origin at t=2 seconds?

object B

A hypothetical planet orbits a star with mass one-half the mass of our sun. The planet's orbital radius is the same as the Earth's. Approximately how many Earth years does it take for the planet to complete one orbit?

sqrt 2

A sphere of mass M, radius r, and rotational inertia I is released from rest at the top of an inclined plane of height h. If the plane is frictionless, what is the speed of the center of mass of the sphere at the bottom of the incline?

sqrt(2gh)

In the absence of air resistance, if an object were to fall freely near the surface of the Moon,

the acceleration is constant; no different than falling on earth

The diagram shows 4 cannons, all with different masses and different angles of acceleration. Horizontal component is the same in all four cases. In which case will the shell have the greatest range?

the cannon with the largest angle

A ball is attached to string and is whirled around in a horizontal circle having a radius R. If the radius of the circle is changed to 4R, and the same centripetal force is applied by the string, the new speed of the ball is which of the following?

twice the original speed F= (mv^2) / R

A person weighing 800 N on Earth travels to another planet with twice the mass and twice the radius of Earth. The person's weight on this other planet is most nearly

400 N

A uniform rope of weight 50N hangs from a hook as shown above. A box of weight 100N hangs from the rope. What is the tension in the rope?

It varies from 100N at the bottom and 150N at the top

Three forces act on an object. If the object is moving to the right in translational equilibrium, which of the following must be true?

The vector sum of the three forces must equal 0 The object must be moving at a constant speed

A car initially travels north and then turns to the left along a circular curve. This causes a package on the seat of the car to slide toward the right side of the car. Which of the following is true of the net force of the package while sliding?

There is not enough force directed toward the center of the circle to keep the package from sliding

The velocity of a projectile at launch has a horizontal component Vh and a vertical component Vv. When the projectile is at its highest point of its trajectory, which of the following shows the vertical and horizontal components of its velocity and the vertical components of its acceleration?

Vertical Velocity: 0 Horizontal Velocity: Vh Vertical Acceleration: g

When an object of weight W is suspended from the center of a massless string as shown above, the tension at any point in the string is

W / (2cosϴ)

At a time t = 0, car X traveling with speed v passes car Y which is just starting to move. Both cars then travel two parallel lanes of the same straight road. a. Which of the following is true at time t = 20 seconds? b. From time t = 0 to time t = 40, the areas under both curves are equal. Therefore, which of the following is true at time t = 40 seconds?

a. Car Y is behind car X b. Car Y is passing car X

A ball is thrown and follows a parabolic path. Point Q is the highest point on the path and points P and R are the same heigh above the ground. a. How do the speeds of the ball at the three points compare? b. Which of the following diagrams best shows the direction of the acceleration at the ball at point P?

a. Q < P = R b. arrow pointing straight down; gravity always points down in projectile motion

A particle continuously moves in a circular path at constant speed in a clockwise direction a. What is the direction of the average velocity during this time? b. What is the direction of the average acceleration?

a. left b. down

Two artificial satellites orbit the earth in circular orbits having radii R1 and R2. If R2 = 2 x R1 the acceleration of the two satellites are related by which of the following?

a2 = (a1) / 4

Two arrows are launched at the same time with the same speed. Arrow A at an angle greater than 45 degrees and arrow B at an angle less than 45 degrees. Both land at the same spot on the ground. Which arrow arrives first?

arrow B; smaller angle does not go as high

Given the three masses, if the coefficient of the kinetic friction between the large mass and table is μ what would be the upward acceleration of the small mass m3 ?

g(m1 -μm2 - m3) / (m1 + m2 + m3)

A new planet is discovered that is twice the Earth's mass and twice the Earth's radius. On the surface of the new planet, a person who weighs 500 N on Earth would experience a gravitational force of

250 N

If a ball is thrown upward with twice the initial speed of another, how much higher will it apex?

4 times

The driver of a car makes an emergency stop by slamming on the car's brakes and skidding to a stop. How far would the car have skidded if it had been traveling twice as fast?

4 times as far

One larger sphere and one smaller sphere have equal densities and are subject only to their mutual gravitational attraction. Which of the following quantities must have the same magnitude for both spheres?

Gravitational force

A door has hinges on the left hand side. Which force produces the largest torque?

Pushing perpendicular from the furthest point from the hinge

Two artificial satellites are put into circular orbit at the same altitude above Earth's surface. The mass of satellite 2 is twice the mass of satellite 1. If the period of satellite 1 is T, what is the period of satellite 2?

T

A ball of mass m is suspended from two strings of unequal length. The magnitudes of the tensions T1 and T2 must satisfy which of the following relations?

T1 < T2 T1 may be longer, but T2 is more vertical

Two identical bowling balls A and B are each dropped from the top of a tall tower. Ball A is dropped 1s before ball B. After ball B is dropped but before ball A strikes the ground, which is true?

The distance between the two balls increases

Is it possible for an object's velocity to increase while its acceleration decreases?

Yes, an example would be a falling object in the presence of air resistance

For the wheel and axle system shown, which of the following expresses the condition required for the system to be in static equilibrium?

am1 = bm2

A block of mass 3m can move without friction on a horizontal table. This block is attached to another block of mass m by a cord that passes over a frictionless pulley. If the masses of the cord and pulley are negligible, what is the magnitude of the acceleration of the descending block?

g/4

A block of weight W is pulled along a horizontal surface at constant speed v by a force F, which acts at an angle with the horizontal. The normal force exerted on the block has magnitude

greater than 0 but less than W

Which object is in its initial position at t=2 seconds?

object A