Chapter 5 Work

Question 1

What is definition form1 joule and equation for work done

What happens to energy when doing work

Answer 1

1 joule is the work done when a force of 1 n moves something by 1m in that direction

Work done = force x distance

When doing work, energy is transferred between different medium
- work done = energy transferred

Question 2

Important about direction of force, which distance do you take?

What force do you take and thus what is the equation

Answer 2

Distance in SAME PLANE AS FORCE ! (Not distance it moved )

2) force = same in the direction of motion so you need component
W= Fxcosy

Question 3

Different types of energies

Electrical? Radiant? Internal?

Answer 3

Chemical, electrical, kinetic , elastic, gravitational

Electrical = energy potential due to position in electric field
Radiant = em waves
Sound
Nuclear
INTERNAL energy is energy sum if kinetic energies of atom

Question 4

Principle, of conservation of energy

Answer 4

Total energy of a closed system remains constant , energy can never be created or destroyed but it can be transferred from one form to another

Question 5

What is gravitational energy and equation

What assumption?

Answer 5

Capacity for doing work as a result of an objects position in a gravatiaonal field

Assuming gravational field is uniform in a system (DOESN”T decrease higher you go)

E = M X G X H

Basically work done to get it there is transferred to GPS, so FxD = GPE, MAD = MGD =MgH

Question 6

What happens to GPE as you lower if you at same velocity

However if velocity change?

Answer 6

If at same velocity it means no KE gained, so all GPE must be transferred to the thermal energy of surrounding air

It is likely a lot of the GPE has converted to KE, like in roller coasters

Question 7

How to derive how fast something hits ground from height, assuming no resistive forces

Answer 7

Assuming no resistive forces, all GPE is transferred to KE

1/2mv2 = MGH
1/2v2 = GH
V = square root 2gh

If know height and know it all transfers, you know speed

Question 8

What is power and equation

Answer 8

Power = work done / time

Rate of work done

Question 9

What is equation of power along a distance of a moving object like car?

Answer 9

Power = speed x force

Because power = wd/ t
Wd= force x distance

Power = fd/t
D/t = speed
Power = force x speed!

Question 10

Finally if they say work what can this be

Answer 10

Any source of energy but try new equation P = S x F first