Work
Define 'Work'
Work is when you use a force to move an object a distance.
When does an object have gravitational potential energy?
When it is at a height above the ground.
When does an object have kinetic energy?
When it is moving.
What does the Work-Energy Theorem state?
The change in kinetic energy of an object is equal to the work done on the object.
Define 'Total Mechanical Energy'
The total mechanical energy is the sum of the kinetic and gravitational potential energy.
What is the formula for work?
W=Fd
What is the formula for gravitational potential energy?
Eg=mgh
What is the formula for kinetic energy?
Ek=(mv2)/2
What is the formula for the Work-Energy Theorem?
W=Ek2-Ek1
What is the formula for total mechanical energy?
ET=Ek+Eg
A person uses a force of 450 N to push a chair 10 m across a room. How much work was done?
4500 J
DAILY DOUBLE
76440 J
A car with a mass of 1,000 kg is moving at a velocity of 20 m/s. What is its kinetic energy?
200000 J
A 10 kg sled is pulled across snow. It starts at rest and reaches 4 m/s. How much work was done on the sled?
80 J
A cart of mass 500 kg is moving along a rollercoaster track. At a certain point, it is 20.0 meters above the ground and moving with a speed of 12.0 m/s. What is the total mechanical energy of the cart at this point on the track?
134000 J
A student pushes a box across the floor with a constant force of 50 N. If the student does 600 J of work while pushing the box, how far did the box move?
12 m
An object is 4 meters above the ground and has gravitational potential energy of 196 J. What is its mass?
5 kg
A runner is moving at 5 m/s and has kinetic energy of 1000 J. What is the runner's mass?
80 kg
A 5 kg object is pushed across a frictionless surface and its speed increases from 2 m/s to 6 m/s. How much work was done on the object?
80 J
DAILY DOUBLE
153600 J
Hannah lifts a 4.9 kg object 1.3 m off the ground. How much work was done?
62.4 J
A 15 kg brick has 735 J of gravitational potential energy. How high is it above the ground?
5 m
A scooter has a mass of 50 kg and kinetic energy of 4,500 J. What is its velocity?
13.4 m/s
A 12 kg bicycle accelerates from 3 m/s to 7 m/s over a distance of 20 meters on a flat, frictionless road. What is the magnitude of the constant force?
12 N [fwd]
A 65 kg skateboarder starts from rest at the top of a smooth ramp that is 5.0 meters above the ground. The ramp curves down to ground level, and there is no friction. Determine the speed of the skateboarder just before reaching the bottom of the ramp.
9.9 m/s