Physics Final Concept Questions

You are standing on a skateboard, initially at rest. A friend throws a very heavy ball towards you. You can either catch the object or deflect the object back towards your friend (such that it moves away from you with the same speed as it was originally thrown). What should you do in order to MINIMIZE your speed on the skateboard?

Catch the ball

In simple harmonic motion, the speed is greatest at that point in the cycle when the

magnitude of the acceleration is a minimum

If the torque on an object adds up to zero the

object could be both turning and accelerating linearly

Consider a plot of the displacement (x) as a function of the applied force (F) for an ideal elastic spring. The slope of the curve would be the

reciprocal of the spring constant

A rock is underwater in a shallow lake. As the rock sinks deeper and deeper into water, the buoyant force on it

remains constant

A train car moves along a long straight track. The graph shows the position as a function of time for this train. The graph shows that the train

slows down all the time

A certain planet has an escape speed V. If another planet of the same size has twice the mass as the first planet, its escape speed will ne

sqrt2V

At which moment shown is the speed of the object the greatest?

C (steepest)

If the mass of the earth and all objects in it were suddenly doubles, but the size remained the same, the acceleration due to gravity at the surface would become

2 times what it is now

The graph represents the position as a function of time for an object in one-dimensional motion. Identify which statement below correctly identifies the times at which the velocity of the object is greater than zero?

3-4 seconds

Planet Z-34 has a mass equal to 1/3 that of Earth, a radius equal to 1/3 that of Earth, and an axial spin rate 1/2 that of Earth. With g representing, as usual, the acceleration due to gravity on the surface of Earth, the acceleration due to gravity on the surface of Z-34 is

3g

A block initially at rest is allowed to slide down a frictionless ramp and attains a speed, v, at the bottom. To achieve a speed, 2v, at the bottom, how many times as high must a new ramp be?

4

An object is moving with constant non-zero acceleration along the +x-axis. A graph of the velocity in the x direction as a function of time for this object is

A straight line making an angle with the time axis

If A and B are nonzero vectors for which A*B=0, it must follow that

AXB=AB

At which moment shown is the speed of the object the smallest?

B (flattest)

Two identical balls are thrown directly upward, ball A at speed v and ball B at speed 2v, and they feel no air resistance. Which statement about these balls is correct?

Ball B will go four times as high as Ball A because it had four times the initial kinetic energy

4.0-kg object is moving with speed 2.0 m/s. A 1.0-kg object 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?

Both objects travel the same distance

The graph shows position as a function of time for two trains running on parallel tracks? Which is true?

Both trains have the same velocity at some time before Tb

A car is being towed at constant velocity on a horizontal road using a horizontal chain. The tension in the chain must be equal to the weight of the car in order to maintain constant velocity

False

As a tile falls from the roof of a building to the ground its momentum is conserved

False

If the acceleration of an object is negative, the object must be slowing down

False

If you swing a bucket of water fast enough in a vertical circle, at the highest point the water does not spill out because an outward force balances the pull of gravity on the water

False

In order to lift a bucket of concrete, you must pull up harder on the bucket than it pulls down on you

False

There must be equal amounts of mass on both sides of the center of mass of an object

False

A ball drops some distance and loses 30 J of gravitational potential energy. Do NOT ignore air resistance. How much more kinetic energy did the ball gain?

Less than 30 J

For the vectors shown in the figure, which statement is true?

S=M-N

In both cases shown a box is sliding across a floor with the same kinetic coefficient of friction and the same initial velocity. The only difference between the two cases is the mass of the box. In which case will the box slide the furthest before coming to rest?

Same

A uniform disk, a uniform hoop, and a uniform solid sphere are released at the same time at the top of an inclined ramp. They all have the same radius and roll without slipping. In what order do they reach the bottom of the ramp?

Sphere, disk, hoop

A mass M is attached to an ideal massless spring. When this system is set in motion with amplitude A, it has a period T. What is the period if the amplitude of the motion is increased to 2A?

T

A box of mass m is pulled with a constant acceleration, a, along a horizontal frictionless floor by a wire that makes an angle of 15° above the horizontal. If T is the tension in this wire, then

T>ma

A battleship simultaneously fires two shells at the enemy ships. If the shells follow the parabolic trajectories shown, which ship gets hit first?

The farer one

An object is moving forward with a constant velocity. Which statement about this object must be true?

The net force on the object is zero

Consider a uniform solid sphere of radius R and mass M rolling without slipping. Which form of kinetic energy is larger, translational or rotational?

Translational kinetic energy is larger than its rotational kinetic energy

If the dot product of two nonzero vectors is zero, the vectors must be perpendicular to each other

True

If the graph of the position as a function of time for an object is a horizontal line, the object cannot be accelerating

True

When an object is solely under the influence of conservative forces, the sum of its kinetic and potential energies does not change

True

Is it possible for a system to have negative potential energy?

Yes, since the choice of the zero potential energy is arbitrary.

Which path has the greatest initial vertical velocity component?

all the same

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 over the package

If an irregularly shaped object (such as a wrench) is dropped from rest in a classroom and feels no air resistance, it will accelerate

but it will not spin

As the speed of a moving fluid increases, the pressure in the fluid

decreases

If we double only the mass of a vibrating ideal mass-and-spring system, the mechanical energy of the system

does not change

You swing a bat and hit a heavy box with a force of 1500 N. The force of the box exerts on the bat is

exactly 1500 N whether or not the box moves

A frictionless pendulum released from 65 degrees with the vertical will vibrate with the same frequency as if it were released from 5 degrees with the vertical because the period is independent of the amplitude and mass

false

If two vectors are perpendicular to each other, their cross product must be zero

false

At a certain depth in the ocean, the absolute pressure is p. If you go to twice that depth (treating the water as incompressible) the

gauge pressure will be doubled

A ball is tossed vertically upward. When it reaches its highest point (before falling back downward) the velocity

is zero, acceleration is directed downward, and the force of gravity acting on the ball is directed downward

A baseball is thrown vertically upward and feels no air resistance. As it is rising

its momentum is not conserved, but its mechanical energy is conserved

A brick is resting on a rough incline as shown in the figure. The friction force acting on the brick, along the incline, is

less than the weight of the brick

A block and a ball have the same mass and start at rest at the top of identical ramps. The block slides down the ramp without friction and the ball rolls down the ramp without slipping. Which one gets to the bottom of the ramp first?

the block

Two objects, on of mass, m, and the other of mass, 2m, are dropped from the top of a building. When they hit the ground

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

A 1.0-kg block and a 2.0-kg block are pressed together on a horizontal frictionless surface with a compressed very light spring between them. They are not attached to the spring. After they are released and have both moved free of the spring

the lighter block will have more kinetic energy than the heavier block

A compact car and a large truck collide head on a stick together. Which undergoes the larger momentum change?

the momentum change is the same for both vehicles.

A basketball is moving in projectile motion. The ball's velocity at the top of its trajectory is equal to

the x-component of the initial velocity

Consider an object floating in a container of water. If the container is placed in an elevator that accelerates upward

there is no difference

When you ride a bicycle, in what direction is the angular velocity of the wheels?

to your left

A satellite is orbiting the earth. If a payload of material is added until it doubles the satellite's mass, the earth's pull of gravity on this satellite will double but the satellite's orbit will not be affected

true

If two vectors point in opposite directions, their cross product must be zero

true

The angular momentum of a system remains constant when

when no torque acts on the system

The simple harmonic motion of an object is described by the graph shown in the figure. What is the equation for the position x(t) of the object as a function of time t?

x(t)=(4.0m)cos[(2pi/8.0s)t-pi/3.0]