Kinematics
A ball is thrown straight up into the air. What are the magnitudes and directions of the velocity and acceleration of the ball at the highest point of its trajectory?
Velocity 0, Acceleration downwards at g
A 10 kg box is sitting at rest on a horizontal floor. What is the normal force acting on the box?
98 N
A ball is dropped from a height of 10 meters. As it falls, what happens to the total energy of the ball and the ball-earth system?
Energy of ball (kinetic) increases, energy of the ball-earth system remains constant.
In a perfectly elastic collision, which quantities are conserved?
Kinetic energy and momentum of the system of objects
Which angular quantity is always conserved in the absence of external torques?
Angular momentum
A car starts from rest and accelerates uniformly at 2 m/s2. How far does it travel in the first 5 seconds?
25 m
A 5 kg object experiences a net force of 15 N to the right. What is the object's acceleration?
3 m/s2 rightward
A person pushes a box 3 meters across a floor with a constant horizontal force of 10 N. If the force is in the direction of motion, how much work is done on the box?
30 J
What is the momentum of a 2 kg cart moving at 3 m/s?
6 kg m/s
A wheel starts from rest and has a constant angular acceleration of 2.0 rad/s2. How much angle (in radians) does it sweep through in the first 4 seconds?
The velocity vs. time graph of a moving object with a negative initial velocity is a straight line with a negative slope. What can you conclude about the object’s motion?
Speeding up in the negative direction.
A 3 kg block is pulled to the right with a 20 N force across a horizontal surface. The frictional force is 8 N. What is the acceleration of the block?
4 m/s2
A roller coaster car of mass 500 kg starts from rest at the top of a 20 m hill. Assuming no friction, what is its speed at the bottom of the hill? Assume g = 10 m/s2
20 m/s
A 0.5 kg ball moving at 4 m/s is brought to a stop in 0.2 seconds. What is the magnitude of the average force applied?
10 N
A solid disk (mass = 2 kg, radius = 0.5 m) has a net torque of 1.0 N·m applied to it. What is its angular acceleration?
4 rad/s2
An object is thrown downward from a height of 60 m with initial speed 5 m/s. How long does it take to reach the ground? Assume g = 10 m/s2
Around 3 s
A 6 kg object hangs from a rope and is accelerating upward at 2 m/s2. What is the tension in the rope? Assume g = 10 m/s2
72 N
A ball is thrown straight up. Ignoring air resistance, at what point during its motion (height) is the kinetic energy equal to the potential energy?
At the midpoint of its height.
A 1.5 kg cart moving at 2 m/s to the right collides elastically with a 1.5 kg cart initially at rest. What are their velocities after the collision?
Cart 1: 0 m/s. Cart 2: 2 m/s
A uniform solid sphere (mass = 3.0 kg, radius = 0.2 m) rolls without slipping down a 1.2 m high ramp. What is its speed at the bottom in m/s? Assume g = 10 m/s2 and moment of inertia of the sphere is 2/5MR2
Around 4.1 m/s
Ball A is dropped from rest from 40 m. Ball B is thrown downward at 10 m/s. How much sooner does Ball B hit the ground?
Around 2 seconds.
A person is standing on a scale in an elevator that is accelerating upward. The person’s mass is 70 kg. How does the weight measured by the scale compare to the person's actual weight?
More than their actual weight.
A 2 kg object is moving at 3 m/s on a frictionless surface. A constant force of 4 N is applied in the direction of motion for 5 meters. What is the final speed of the object?
5.4 m/s.
A small cart is rolling at constant speed on a frictionless track. A student standing next to the track throws a heavy ball straight down into the cart, and the ball lands and stays inside. Immediately after the ball lands in the cart, what happens to the speed of the cart?
Cart stays at the same speed.
Two objects, a solid disk and a hoop, both of mass M and radius R, are released from rest and roll down the same incline from the same height. Which object reaches the bottom first, and why?
Solid disk because it has a lesser moment of inertia.