Graphing KE
When you make a graph showing how kinetic energy changes with speed, what would the line look like?
It would have a steep curve
An object has a mass of 2 kg and moves at 3 m/s. What is its kinetic energy?
9 J
What is kinetic energy?
The energy of motion
When a ball rolls down a hill, what type of energy is it gaining as it speeds up?
Kinetic Energy
Why does a truck moving at the same speed as a car have more kinetic energy?
If two objects have the same mass but one moves faster, where would the faster object's point be on a KE vs. speed graph?
It would be higher up on the graph
A skateboarder has 50 J of kinetic energy and a mass of 5 kg. How fast is the skateboarder moving?
approximately 4.47 m/s
What does “mass” mean?
The amount of matter in an object
How does friction affect the kinetic energy of a moving object?
It reduces the object's KE
How does a roller coaster show changes between potential and kinetic energy?
On a graph of kinetic energy vs. mass, what happens to the kinetic energy when the mass gets larger but the speed stays the same?
The kinetic energy increases in a straight line (linear growth)
What is the kinetic energy of a 10 kg object that isn’t moving?
0 J
What does “speed” mean?
the rate that something moves
When a moving bike stops, what happens to its kinetic energy?
It converts into Potential Energy
Why does a small rock thrown really fast have more kinetic energy than a slow-moving bowling ball?
Because speed increases KE exponentially
If two balls roll at the same speed but one has more mass, which one would be higher on a KE vs. mass graph?
The one with more mass
If you double the mass of an object but keep the speed the same, how does its kinetic energy change?
The KE would also double
What is “energy”?
The ability to do work
If two balls bump into each other, how is kinetic energy transferred between them?
The energy is transferred from the faster ball to the slower ball
How can knowing about kinetic energy help engineers make cars safer?
They know how energy is transferred in an impact
A student draws a flat (horizontal) line for a graph of KE vs. speed. What mistake might they have made?
They may have been graphing the mass
or
The speed did not increase
If an object’s speed doubles, how many times greater is its kinetic energy?
four times greater
In the formula for kinetic energy (KE = ½mv²), what does the letter “v” stand for?
Velocity
Give one example of potential energy changing into kinetic energy in everyday life.
Answers will vary:
- gravity pulling something down
- a stretched rubber band snapping back to normal
Why does going a little faster take a lot more energy once you’re already moving quickly?
Because speed exponentially increases KE