# Physics Final

A player kicks a soccer ball in a high arc toward the opponents goal. At the highest point in its trajectory

neither the ball's velocity nor its acceleration are zero

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

remains 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

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

the astronaut is falling

Two objects one of mass m and the other of mass 2m are dropped from the top of the building. If there is no air resistance when they hit the ground

the heavier one will have twice the kinetic energy of the lighter one

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 you do on Earth

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 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?

(no horizontal forces act on A)

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

700N

In which of the following situations is the kinetic energy of the object is decreasing?

A baseball is heading upward after being thrown at an angle

An object is moving with a constant non-zero velocity in the +x direction. The position vs time graph is

A parabolic curve

A person stands on the edge of the cliff and throws 3 identical rocks with the same speed. Rock x vertically upwards, rock y horizontally, and rock z vertically downward, which rock hits the ground with the most speed if there is no air resistance?

All hit the ground at the same speed

Which of the following situations is impossible?

An object has constant non-zero velocity and changing acceleration.

A 4kg object is moving with speed 2m/s. A 1kg object is moving with speed 4m/s. Both objects encountered the same constant braking force, and are brought to rest. Which object travels a greater distance before stopping?

Both objects travel the same distance

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 snowball

Two objects are dropped from a bridge, an interval of 1.0s apart. Air resistance is negligible. During the time that both objects continue to fall their seperation

Decreases at first, but then stays constant

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

Earth and the satellite feel exactly the same force

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 other.

F

If the velocity of an object is zero, then that object cannot be accelerating?

False

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 a car traveling to the west (-x direction) begins to slow down as it approaches a traffic light. Which statement concerning it's acceleration must be correct?

It's acceleration is positive

A rock is thrown from the uper edge of a tall cliff at some angle above horizontal. It reaches its highest point and starts falling down. Which of the following statements about the rocks motion is true just before it hits the ground?

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

You are making a circular turn in your car on a level road when you hit a big patch of icem 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

Two men, Joel and Jerry, push against a car that has stalled, trying unsuccessfully to get it moving. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do on the car.

Neither of them does any work

As shown in the figure, a woman is straining to lift a large crate, but without success because it's too heavy. We denote the forces on the crate as follows: P is the magnitude of the upward force being exerted on the crate 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 level road at a constant speed. What is the direction of the friction force on the car due to the road.

Perpendicular to the curve inward

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 small car is rolling freely on an inclined ramo with a constant acceleration of 0.50m/s in -x direction. At time t=0 the cart has a velocity of 2.0m/s in the +x direction. If the cart never leaves the ramp, which of the following statements correctly describes the motion of the cart at time t>5s?

The cart is traveling in the -x direction and is speeding up

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

The force of friction exerted by the ground on a person

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

The net force of the object is zero

An objects velocity(v) as a function of time(t) is given in the graph above. Which of the following statements is true about the motion of the object?

The object's initial and final positions are teh same

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

A stone can slide down one of different frictionless ramps will the speed of the ball be the greatest at the greatest at the bottom?

The speed of the ball will be the same for all the ramps

The motion of a car and a truck along a straight road are represented by the velocity-time graphs in the figure. The two vehicles are initially alongside each other at t. At time I what is true of the distances traveled by the vehicles since time t=0?

The truck will have traveled farther than the car

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

You threw a baseball straight up. Compare the sign of work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down

The work is negative on the way up and positive on the way down

Swimming at the waterpark have a choice of two frictionless waterslides as shown in the figure. Although both slide drop over the same height Hm slide 1 is straight while slide 2 is curved dropping quickly at first and then evening out. How does the speed of V1 of a swimmer reaching the bottom of the slide 1 compare with the V2, the speed of the swimmer reaching the end of slide 2?

V1=V2

A push of magnitude P acts on a box of weight W as shown in the figure. The push is directed at an angleΘ below the horizontal cord. The mass of P is greater than that of Q. A horizontal force of F is applied to box Q as shown in the magnitude of the force exerted by the connecting cord on body P is

W+Psinθ

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

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

be directly over the plane

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

equal to the weight of the bucket

Suppose a ball is thrown straight up and experiences no appreciable air resistance. What is its acceleration just before it reaches its highest point

exactly g

Suppose a ball is thrown straight up and experiences no appreciable air resistance. What is its acceleration just before it reaches its highest point?

exactly g

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

false

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

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 g, the acceleration due to gravity at the surface of the earth?

g/8

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

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

is always zero

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

is directed toward the center of its circular path

Suppose a car traveling to the west (-x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct?

its acceleration is positive

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