Energy & work in mechanics

Question 1

What is kinetic energy?

Answer 1

The energy an object possesses due to its motion

Question 2

How much kinetic energy would an object have when it is stopped?

Answer 2

0

Question 3

What is gravitational potential energy?

Answer 3

The energy stored in an object based on its mass and height above a surface

Question 4

Describe each variable in E=1/2mv2

Answer 4

E= the kinetic energy (J)
m= mass (kg)
v= velocity (speed) (meter/sec)

Question 5

If a bus weighs 10 000Kg travels at 50km/h how much kinetic energy does it have?

Answer 5

Ek= 964660.5 J

Question 6

If a bus weighs 10 000Kg and its kinetic energy is 980KJ then how fast was it going? (m/s and km/h)

Answer 6

14m/s

50.36km/h

Question 7

Describe the variables in Ep=mgh

Answer 7

Ep= Potential energy (Joules)
m= mass (Kg)
g= gravitational field intensity (Earth=9.8m/s2)
h= height above the surface (m)

Question 8

If a car weighs 10 000Kg and is dropped from a 1km distance, how much potential energy would you absorb if you were hit?

Answer 8

Ep= 98 000 000 J

Question 9

What does Em mean?

Answer 9

Mechanical energy

Question 10

How much work you do is related to what?

Answer 10

How much energy is required to move an object over a certain distance

Question 11

Describe the variable in W=(F)(delta d)

Answer 11

W=work (J)
F= force (N)
delta d= distance (m)

Question 12

If it took 50KJ to push a desk 5 meter across the floor, what force was required to do it?

Answer 12

N= 10 000N

Question 13

What is equal to the change in total mechanical energy?

Answer 13

The total amount of work you do

Total energy= Ek+Ep

Question 14

Movement of objects horizontally is what type of energy?

Answer 14

Kinetic

Question 15

Movement of objects vertically is what type of energy?

Answer 15

Potential

Question 16

Describe the variables in F=mg

Answer 16

F=force (N)
m= mass (KJ)
g=gravity (m/s2) or (N/kg)

Question 17

What is the weight of a person whose mass is 50Kg on Earth?

Answer 17

F=490N

Question 18

Describe mass

Answer 18

• Mass is our weight on Earth.
• The amount of stuff (atoms) that make us up
• DOES NOT CHANGE no matter what planet we are on

Question 19

Describe weight

Answer 19

• Is dependent on the force or pull of gravity on you

- CAN CHANGE on a different planet or moon

Question 20

Do we weigh less on the moon?

Answer 20

yes. less gravity