##### Chapter 9 Motion and Energy

8th grade

How do you determine if any object is in motion?

determine if it' distance from a reference point is changing

What is a reference point?

A place or object used for comparison to determine if something is in motion.

What is the length of a path between two points?

distance

What is displacement?

the length and direction of an object has moved from its starting point

How is speed calculated?

distance/time

If you know the total distance of a trip and the total time it took, what can you calculate?

average speed

What is instantaneous speed?

the rate at which an object is moving at a given instant in time

What is speed in a given direction?

velocity

How is slope calculated?

rise/run

What three kinds of change in motion are called acceleration?

increasing speed, decreasing speed, and changing direction

Is there a change in acceleration if a person is driving at a constant rate in a circle?

Yes, they are changing direction.

How is acceleration calculated?

(final velocity - initial velocity)/time

Measurements of acceleration are given in units of?

distance/time^2

What is kinetic energy?

the energy of motion

How is kinetic energy calculated?

1/2 * mass * speed^2

What type of energy has the potential to do work?

potential energy

How is gravitational potential energy calculated?

weight * height

The potential energy of objects that can be stretched or compressed is called what?

elastic potential energy

How is mechanical energy calculated?

kinetic energy + potential energy

What does the law of conservation of energy state?

energy cannot be created nor destroyed