Types of Energy
This type of energy is stored due to an object's position or height above the ground.
What is gravitational potential energy?
An object is dropped from rest. What two types of energy appear in the bar chart during the fall?
What are gravitational potential energy and kinetic energy?
What two types of mechanical energy are conserved when no external forces do work?
What are kinetic energy and potential energy?
Work is done when an object is moved by a __.
What is a force?
Power is the rate at which __ is done.
What is work?
Energy due to motion, based on mass and velocity.
What is kinetic energy?
In a bar chart for a spring-loaded toy just before release, what type of energy dominates?
What is spring energy?
True or False: If only gravity does work, mechanical energy is conserved.
What is True?
If no work is done on an object, what happens to its energy?
It stays the same.
What is the formula for power in terms of work and time?
What is Power = Work ÷ Time?
Energy stored in compressed or stretched objects, like springs and rubber bands.
What is spring potential energy?
In a bar chart for a roller coaster at the top of a hill, what type of energy is maximized?
What is gravitational potential energy?
A 2 kg rock falls from a cliff. What happens to its potential energy as it falls?
It decreases and transforms into kinetic energy.
A force of 10 N moves a box 5 meters. How much work is done?
50 Joules.
A machine does 600 Joules of work in 3 seconds. How much power does it output?
200 Watts.
Units used for energy
What is chemical energy?
In an energy bar chart, if total bar height stays constant, what principle does this show?
What is conservation of energy?
A skier starts from rest and goes down a frictionless hill. What happens to total mechanical energy?
It stays constant.
A car’s engine does 5000 J of work to accelerate it. What happens to the car’s kinetic energy?
It increases by 5000 J.
True or False: A more powerful machine always does more work.
What is False? (It may just do the same work faster.)
Ug+Us+K
Total Mechanical Energy
If friction is present, how would the energy bar chart change?
Some of the mechanical energy bars shrink, and a new thermal energy bar appears.
If a ball reaches half its initial height on the bounce, what energy is lost and where does it go?
Some mechanical energy is lost.
State the Work-Energy Theorem.
What is "the net work done on an object equals its change in kinetic energy"?
A 60 Watt lightbulb is on for 2 minutes. How much energy does it use?
7200 Joules. (Energy = Power × Time → 60 W × 120 s = 7200 J)