Kinematics
What is the equation for average acceleration?
What is the kinetic friction force on an object of mass 37 kg as it moves over a surface where μk = 0.22?
80 N
Object is moving at velocity v with mass m. If both the velocity and the mass of the ball are tripled, the kinetic energy is increased by a factor of?
What is 27
In which types of collisions is kinetic energy conserved?
elastic
If you have a flat tire, and you’re using a wrench to loosen the nuts that hold the tire rim to the axle, is it advantageous to have a longer wrench or a shorter one? Why?
longer wrench will maximize the torque, which results in a greater acceleration
If you are given a velocity vs. time graph and are asked to find the position of an object at a given time - what should you do?
Area under the curve
A couch of 150 kg is pushed on a carpeted floor with μs = 0.33 and μk = 0.22. If it is pushed with a force of 400N, does it move (provide an explanation).
No, the force of static friction is greater than the applied force.
A student swings a ball of mass m around his head in a perfectly circular, horizontal orbit of radius r, with a constant Tension. How much work is done by the force of tension? Write your answers in terms of m, r, a and fundamental constants.
0
Object 1 moves with an initial speed of v towards object 2, which has a mass half that of object 1. If the final speed of both objects after colliding is 0, what must have been the initial speed of object 2, assuming no external forces?
2v
An ice skater is spinning very fast with her arms tucked into her side. She wants to slow her rate of rotation. Assuming friction is negligible how can she change her rotation rate?
Bring arms out away from her central mass
A block is projected up a frictionless plane with an initial speed vo. The plane is inclined 30° above the horizontal. What is the approximate acceleration of the block at the instant that it reaches its highest point on the inclined plane?
Object X has traveled four times as far as object Y.
A 42 kg wagon is being pulled with a rope that makes an angle of 460 with the horizontal. The applied force is 449 N and the coefficient of kinetic friction between the wagon and the ground is 0.21.
What is the normal force acting on the wagon?
92N
A 3.0 kg toy falls from a height of 10.0 m. Just before hitting the ground, what will be it's kinetic energy?
What is 300 J?
A ball of mass m traveling horizontally with a velocity v strikes a massive vertical wall and rebounds back along its original direction of travel. What is the magnitude of the impulse delivered by the wall to the ball?
2mv
Calculate the angular momentum of a ballet dancer who is spinning at 1.5 rev/sec. The dancer has I = ½ MR squared, with a mass of 62 kg, a height of 1.6 m and a radius of 0.16 m.
7.5 kgm2/s
At a given time, an object in free fall has velocity 5.0 m/s in the upwards direction. The approximate velocity (magnitude and direction) of the object one second later is...
What is 5 m/s downward
A box of mass 47 kg is sliding down a frictionless incline that makes an angle of 34 degrees with the horizontal. What is its acceleration?
5.5m/s2
A block of mass m is placed on a frictionless inclined plane with an incline angle θ. The block is just in a contact with a free end on an unstretched spring with a spring constant k. If the block is released from rest, what is the maximum compression in the spring. Give in terms of m, θ, k and fundamental constants.
2mg sinθ /k
The area under the curve of a force time graph is
Impulse
A student is at rest on a stool that may freely spin about its central axis of rotation. As the stool spins, the student holds onto two dumbbells as the stool spins at an angular speed of 1.2 rad/s with the student’s arms completely stretched out from the student’s body. At this instant, the student-dumbbell system has rotational inertia of 6 kg·m2. The student then brings their arms close to their body, and rotational inertia of the student-dumbbell system is changed to 2 kg·m2. What is the new angular speed of the student?
3.6 rad/s
A block is projected up a frictionless plane with an initial speed vo. The plane is inclined 30° above the horizontal. What is the approximate acceleration of the block at the instant that it reaches its highest point on the inclined plane?
5 m/s2 down the incline
A ball with a mass m is fastened to a string and is swung in a vertical circle. When the ball is at the lowest point of the circle, what is the force of tension? (Write answer in terms of m,a and fundamental constants)
mg + ma
A student pushes a box across a horizontal surface at a constant speed of 0.6 m/s. The box has a mass of 40 kg, and the coefficient of kinetic friction is 0.5. The power supplied to the box by the person is:
120 W
A wooden block of mass M is moving at speed v in a straight line. How fast would the bullet of mass m need to travel to stop the block, assuming that the bullet becomes embedded inside the wooden block?
mv/m
A system consists of a disk rotating on a frictionless axle and a piece of clay moving toward it. The outside edge of the disk is moving at a linear speed v, and the clay is moving at speed v/2. The clay sticks to the outside edge of the disk. How does the angular momentum of the system after the clay sticks compare to the angular momentum of the system before the clay sticks, and what is an explanation for the comparison?
It is the same because there is no external torque acting on the system.