Forces
Three forces are balanced as they act on an object. If the 1st is a 6N force to the left, and the 2nd is a 2N force to the right, the 3rd must be ...
... a 4N force to the left.
What is the ability to do work?
Energy
In the equation for power, what does the W in the equation stand for?
Work
A high diver steps off a diving platform that is 10 meters above the water. As he falls, what is his gravitational potential energy is converted to?
Kinetic Energy
Which types of collisions conserve momentum?
All of them
What is the measure of how hard gravity pulls on an object?
Weight
A 10.0-newton force is used to push a 2.00-kilogram cart a distance of 4.00 meters. What is the work done on the cart by the push?
40 J
What force produces heat?
The force of friction
If we ignore friction, what happens to the total energy of a pendulum as it swings upward? (Does it increase, decrease, or stay the same)?
It stays the same
A child is on a sled moving down a hill at 30 m/s. The combined mass of the sled and child is 80-kg. What is the momentum of the child and sled?
-2400 kg m/s
A net force of 45 N is applied horizontally to a 9-kilogram block resting on a table. What is the magnitude of the acceleration of the block?
5 m/s2
A 4 kg box is pulled 3 m across the floor. The force of friction is 10 N. How much work does the force of friction do?
-30 J
What is spring potential energy?
Energy stored in the stretching or squishing of an object
Imagine a semicircular frictionless track whose ends are at a vertical height h. A skateboarder holding onto a rail at the top of one end of the track lets go and slides past the bottom of the track. How high does the skateboarder rise on the other side of the track?
To height h
Two carts of unequal masses are at rest on a level surface with a compressed spring between them. Cart A has a mass of 3 kg and Cart B 5kg. When the spring releases, the carts move apart, with cart A moving 4 m/s to the right. What is the combined momentum of the two carts after the spring is released?
Zero
On the surface of planet X, the acceleration due to gravity is 15 m/s2. What is the weight of a 5.0 kg mass located on the surface of planet X?
75 N
A lab cart is being pulled up a ramp. If the angle between the ramp and the horizontal increased, what happens to the force required and the work done? (Does each increase, decrease, or stay the same?)
The force increases but the work stays the same
A 60kg high-diver is on a diving platform that is 5 meters above the water. What is the high diver’s gravitational potential energy?
3000 J
An engine uses 4000 N of force to move a car 100m in 10 s. What is its power?
40,000 W
A pool ball (0.15 kg) rolls at a speed of 3 m/s and hits a golf ball (0.05 kg), which is initially at rest. After the collision, the pool ball stops moving and the golf ball rolls off at some speed. What is the speed of the golf ball?
9 m/s
If the sum of all the forces acting on a moving object is zero, what will the object do?
Continue moving with constant velocity
As a 1000-N car moves 500m north, how much work does the force of gravity do?
Zero
A 1.0 kg bird is gliding with a speed of 4 m/s. What is the bird’s kinetic energy?
8 J
It takes Sarah 2 s to lift a book using 200 J of energy. What is the power that Sarah uses?
100 W
Two carts have equal mass. Before the collision, cart A is moving to the left at a velocity of 2 m/s and cart B is at rest. After the collision, they stick together. What is the velocity of each cart after the collision?
Both carts move 1 m/s to the left