Physics Unit 4 Energy

Question 1

What is the unit of work? How is this unit mathematically derived?

Answer 1

Joule. (J), N*m

Question 2

state the definition of power.

Answer 2

How fast work is done, P= work/time

Question 3

What is the unit of power? How is this unit mathematically derived?

Answer 3

Joule/sec

Question 4

What is the definition of energy?

Answer 4

Capacity to do work

Question 5

What is the unity of energy?

Answer 5

Joule (J)

Question 6

What are the two types of mechanical energy?

Answer 6

Potential and kinetic

Question 7

State the definition of potential energy.

Answer 7

Stored energy due to its position

Question 8

List some examples of things that can possess potential energy,

Answer 8

raised objects or springs

Question 9

what is the acceleration of gravity on earth? What does that tell us about a falling object?

Answer 9

9.81 m/s2 …..

Question 10

Calculate the gravitational potential energy possessed by a 1000 kg object on earth that has been raised to a height of 4m:

Answer 10

1000 kg *9.81m/s2 * 4m =39,240 J

Question 11

write the equation for gravitational potential energy.

Answer 11

PE=mgh

Question 12

List some ways in which energy may be stored.

Answer 12

Raised objects or springs

Question 13

State the definition of kinetic energy

Answer 13

K.E. = 1/2mv2

Question 14

Calculate the kinetic energy possessed by a 4kg object traveling at 3 m/s:

Answer 14

(1/2) (4kg)(3m/s)2= 18 J (the 2 is for squared)

Question 15

List some ways that energy may be stored

Answer 15

Raised Objects or Springs

Question 16

State the definition of Kinetic energy.

Answer 16

energy in motion

Question 17

Write the equation for kinetic energy.

Answer 17

K.E. = 1/2 mv 2(2 is for squared)

Question 18

State the law of conservation of energy:

Answer 18

Energy can not be created or destroyed. It only changes from one form to another.

Question 19

State the definition of a machine:

Answer 19

A device for multiplying forces or changing the direction of forces.
Fd input = Fd output

Question 20

Write the equation for efficiency:

Answer 20

Efficiency = useful energy output/ total energy output

Question 21

Write the equation for work:

Answer 21

w=Fd