Physics Exam 2
A 50. kg mass is at rest on a frictionless surface. An unknown force pushes the mass for 5.0 seconds until the mass reaches a velocity of 3.0 m/s. What was the magnitude of the impulse acting on the mass?
150 kg-m/s
A tire is rolling along a road, without slipping, with a velocity v. A piece of tape is attached to the tire. When the tape is opposite the road (at the top of the tire), the velocity of the tape with respect to the road is:
2v.
A constant nonzero net torque is exerted on an object that is free to rotate. Which of the following is constant?
Angular acceleration.
You are riding your bicycle due east. You slow down your bicycle. What are the directions of angular velocity and angular acceleration of bicycle wheels during slowing down?
Angular velocity points NORTH and angular acceleration points SOUTH.
Two objects, one of mass m and the other of mass 2m, are thrown directly upward with the same velocity at the same time from ground level and feel no air resistance. Which statement about these objects is true?
At its highest point, the heavier object will have twice as much gravitational potential energy as the lighter one because it is twice as heavy.
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.
Two solid spheres of different radii and different masses roll down an incline surface without slipping, starting from rest at the same height. Sphere A has a greater mass and sphere B has a greater radius. Which reaches the bottom first?
Both at the same time.
In a collision between two objects having unequal masses, how does the magnitude of the impulse imparted to the lighter object by the heavier one compare with the magnitude of the impulse imparted to the heavier object by the lighter one?
Both objects receive the same impulse.
Which of following statements is TRUE about momentum?
It is a vector, with a magnitude and a direction.
Two blocks of ice, one four times as heavy as the other, are at rest on a frozen lake. A person pushes each block the same distance d. Ignore friction and assume that an equal force 𝐹⃗ is exerted on each block. Which of the following statements is true about the kinetic energy of the heavier block after the push?
It is equal to the kinetic energy of the lighter block.
When an object is moving only under the influence of conservative forces, which of the following statement is TRUE?
Its mechanical energy does not change.
On a smooth horizontal floor, an object slides into a spring which is attached to another mass that is initially stationary. When the spring is most compressed, both objects are moving at the same speed. Ignoring friction, what is conserved during this interaction?
Momentum and mechanical energy
Which one of the following statement is true?
Momentum is a vector, with a magnitude and a direction.
The moment of inertia of an object depends on which of the following factors?
The axis about which the object is rotated.
You throw a ball upward. When the ball is moving up, what can you conclude about the gravitational force exerted on the ball?
The gravitational force does negative work on the ball and decreases its kinetic energy.
When an object travels in a circular path at constant speed, which one of the following statements is wrong?
The object's acceleration is zero.
A small car has a head-on collision with a large truck. Which of the following statements concerning the magnitude of the average force due to the collision is TRUE?
The small car and the truck experience the same average force.
A solid sphere is rolling without sliding about its center of axis with moment of inertia 2MR2/5 along a flat, horizontal plane. The center of mass of the sphere is moving toward the south at constant velocity. Which one of the following statements concerning the translational and rotational kinetic energies of the sphere is true?
The translational kinetic energy is greater than the rotational kinetic energy.
What is true about the work done by a conservative force?
The work done by a conservative force along any closed path is zero OR The work done by a conservative force is always path independent.
For a particle rotating about a fixed axis with angular velocity that changes, which of the following statements is TRUE?
There are both radial acceleration and tangential acceleration
When you ride a bicycle and go forward, in what direction is the angular velocity of the wheels?
To your left.
When a rigid body rotates about a fixed axis, all the points in the body have the same
angular displacement.
A light cart and a heavy steel cart are both pushed with the same force for the same time interval, starting from rest. After the force is removed, the momentum of the light plastic cart is:
equal to that of the heavy steel cart.
A light plastic cart and a heavy steel cart are both pushed with the same force for the same time interval, starting from rest. After the force is removed, the momentum of the light plastic cart is:
equal to that of the heavy steel cart.
Which of the following forces is considered a conservative force?
gravity
A mass is pressed against (but is not attached to) an ideal horizontal spring on a frictionless horizontal surface. After being released from rest, the mass acquires a maximum speed v and a maximum kinetic energy K. If instead the mass initially compresses the spring twice as far,
its maximum speed will be 2v and its maximum kinetic energy will be 4K.
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.
The moment of inertia plays the same role in rotational motion as is played in linear motion by
mass
The momentum of a system is conserved only if
no net external force is exerted on the system.
The center of mass of a system of two non-identical point particles is
on the line joining them and at a point whose distance from each particle is proportional inversely to the mass of that particle.
A block that is attached to an ideal massless spring oscillates vertically. When the speed of the block is a maximum, which of following statements is TRUE?
the magnitude of the force is zero
The change in an object's momentum during a certain time interval is equal to
the net force exerted on the object times the duration of the time interval
If a quantity X is conserved for a certain system and during a certain process, that means
the quantity X for that system does not change in any way during that process.
Two objects with different masses collide with and stick to each other on a frictionless surface. Compared to before the collision, the system of two objects after the collision has
the same amount of total momentum but less total kinetic energy.