AP Physics Semester 1 Study Guide

A push of magnitude P acts on a box of weight W as shown in the figure. The push is directed at an angle θ below the horizontal, and the box remains a rest. The box rests on a horizontal surface that has some friction with the box. The normal force on the box due to the floor is equal to

w+psinθ

A person who normally weighs 700 N is riding in a rather swift elevator that is moving at a constant speed of 9.8 m/s. If this person is standing on a bathroom scale inside the elevator, what would the scale read?

700N

An object is moving with constant nonzero acceleration in the +x direction. The position vs time graph of the object is:

A parabolic curve.

Which of the following situations is impossible?

An object has constant nonzero velocity and changing acceleration

An auto manufacturer advertises that their car can go "from zero to sixty in eight seconds." This is a description of what characteristic of the car's motion?

Average acceleration

Mary and Debra stand on a snow-covered roof. They both throw snowballs with the same initial speed, but in different directions. Mary throws her snowball downward, at 30° below the horizontal; Debra throws her snowball upward, at 30° above the horizontal. Which of the following statements are true about just as the snowballs reach the ground below? (There could be more than one correct choice.)

Debra's snowball will stay in the air longer than Mary's.

When an object moves in uniform circular motion, the direction of its acceleration is...

Directed towards the center of its circular path.

A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will

Directly over the package.

A satellite is in orbit around the earth. Which one feels the greater force?

Earth and the satellite feel exactly the same force.

A bucket is being lowered by a very light rope with a constant downward velocity. The tension on the rope must be:

Equal to the weight of the bucket.

If a ball is thrown straight up w/ negligible air resistance, what is acc. just before the highest point?

Exactly g.

Two small balls, A and B, attract each other gravitationally with a force of magnitude F. If we now double both masses and the separation of the balls, what will now be the magnitude of the attractive force on each one?

F

T or F. If the velocity of an object is zero, then that object can not be accelerating.

False

T or F. If the velocity of an object is zero, then that object cannot be accelerating.

False.

T or F. If you swing a bucket of water fast enough in a vertical circle, at the highest point the water does not spill out. This happens because an OUTward force balances the pull of gravity on the water.

False.

An elevator suspended by a vertical cable is moving downward but slowing down. The tension in the cable must be

Greater than the weight of the elevator.

If a satellite moves with constant speed in a perfectly circular orbit around the earth, what is the direction of the acceleration of the satellite?

Inward toward the earth.

A spaceship is traveling to the Moon. At what point is it beyond the pull of Earth's gravity?

It is never beyond the pull of Earth's gravity.

Suppose that a car traveling to the west begins to slow down as it approaches a traffic light. Which of the following statements about its acceleration is correct?

It's acceleration is positive.

Suppose that a car traveling to the west begins to slow down as it approaches a traffic light. Which of the following statements about its acceleration is correct?

Its acceleration is positive.

A rock is thrown from the upper edge of a tall cliff at some angle above the horizontal. It reaches its highest point and starts falling down. Which of the following statements about the rock's motion are true just before it hits the ground (can be more than one choice)?

Its horizontal velocity component is the same as it was just launched.

Two boxes P and Q on a perfectly smooth horizontal surface are connected by a light horizontal cord. The mass of P is greater than that of Q. A horizontal force F is applied to box Q as shown in the figure, accelerating the bodies to the right. The magnitude of the force exerted by the connecting cord on body P is

Less than f but not zero.

You are making a circular turn in your car on a horizontal road when you hit a big patch of ice, causing the force of friction between the tires and the road to become zero. While the car is on the ice, it

Moves along a straight line path in a direction tangent to the curvature of the turn.

As shown in the figure a woman is struggling to lift a large crate, but without success because it is too heavy. We denote the forces on the crate as follows: P is the magnitude of the upward force being exerted by the crate on the person. C is the magnitude of the vertical contact force on the circle by the floor and W is the weight of the crate. How are the magnitudes of these forces related while the person is trying unsuccessfully to lift the crate?

P+C=W

A car goes around a circular curve on a horizontal road at constant speed. What is the direction of the friction force on the car due to the road?

Perpendicular to the curve inward.

For general projectile motion with no air resistance, the horizontal component of a projectile's velocity...

Remains a non zero constant.

You are in a train traveling on a horizontal track and notice that a piece of luggage starts to slide directly toward the front of the train. From this observation, you can conclude that this train is

Slowing down.

Three boxes are pulled along a horizontal frictionless floor by a constant horizontal pull P. The boxes are connected by very light horizontal strings having tensions T1 and T2 as shown in the figure. Which of the following statements about the tensions is correct? (There could be more than one correct choice.)

T1>T2.

A player kicks a soccer ball in a high arc toward the opponent's goal. At the highest point in its trajectory:

The acceleration and velocity of the ball do not equal zero.

The reason an astronaut in an earth satellite feels weightless is that...

The astronaut is falling.

A person is running on a track. Which of the following forces propels the runner forward?

The force of friction by the ground on the person.

An object is moving with constant non-zero velocity. Which of the following statements about it must be true?

The net force on the object is zero.

If you stood on a planet having a mass four times that of Earth's mass, and a radius two times that of Earth's radius, you would weigh

The same as you do on Earth.

If you pound a feather with a hammer, which one feels a greater force?

The size of the force is always exactly the same on both of them.

Satellite A has twice the mass of satellite B, and moves at the same orbital distance from Earth as satellite B. Compare the speeds of the two satellites.

The speed of B is equal to the speed of A.

Two objects have masses m and 5m, respectively. They both are placed side by side on a frictionless inclined ramp and allowed to slide down from rest without any air resistance. Which one of the following statements about these objects is correct?

The two objects reach the bottom of the ramp at exactly the same time.

Two blocks, A and B, are being pulled to the right along a horizontal surface by a horizontal 100-N pull, as shown in the figure. Both of them are moving together at a constant velocity of 2.0 m/s to the right, and both weigh the same. Which of the figures below shows a correct free-body diagram of the horizontal forces acting on the lower block, B?

[A] (None, this depicts block A with no forces acting on it.)

A hypothetical planet has a mass one half that of the Earth and a radius of twice that of the Earth. What is the acceleration due to gravity on the planet in terms of y, the acceleration due to gravity at the surface of the Earth?

g/8

For general projectile motion with no air resistance, the horizontal component of a projectile's acceleration...

is always zero.