Q1 Chapter 2 - Work, Power, Energy

Question 1

What is/are the unit/s used to express Work?

Answer 1

Newton x Meters (NM) or Joules (j)
& Ergs

Question 2

A 10-kilogram box is on a level floor. An applied force of 100 N moves it to the right at a distance of 2 m. Other forces are acting on the box. Calculate the following:
1. The work done by each force.
2. The total work done.

Answer 2

1. Work = F_d
   (Force x displacement)
   = 100 x 2
   = 200 j

Work = 10kg x 2m
= 98.1 x 2
= 196.2 j

2. Total Work = W1 + W2
   = 200 + 183.6
   = 396.2 J

Question 3

These are the components of
calculating work done on an
object.

Answer 3

Force applied and Displacement

Question 4

What is the Formula for Work?

Answer 4

W = Fd

Question 5

This is the unit of work when
centimeter-gram-second (CGS)
units are used.

Answer 5

Ergs

Question 6

Compare Mass and Weight.

Answer 6

Mass
> refers to how much matter
an object contains
> measured in kg
> always remains the same
> cant be measured directly

Weight
> refers to force exerted on a mass by gravity
> can change with location
> can be measured directly using a scale

Question 7

What is energy? What are its 2 types?

Answer 7

Energy - the capacity to do work

Kinetic Energy - the energy due to motion

Potential Energy - the energy due to position

Question 8

1) Give the formula for Kinetic Energy
2) Give the formula for mass when Kinetic Energy and Velocity is Given

Answer 8

1. (1/2)mv^2
2. 2k ÷ v^2

Question 9

A 9-kg bowling ball slides on the lane at a velocity of 3 m/s. What is the ball’s Kinetic Energy?

Answer 9

KE = (1/2)mv^2
= (1/2)(9)(3)^2
= 40.5 J

Question 10

What is the formula used to find the change in Kinetic Energy?

Answer 10

Change in KE = KEf - KEi

Question 11

What is the Formula used to find KEf and KEi when mass is changing and velocity is constant?

Answer 11

Given Quantities: m1, m2, v

KEf = (1/2)(m2)(v)^2
KEi = (1/2)(m1)(v)^2

Question 12

What is the Formula used to find KEf and KEi when mass is constant and velocity is changing?

Answer 12

Given Quantities: m, v1, v2

KEf = (1/2)(m)(v2)^2
KEi = (1/2)(m)(v1)^2

Question 13

What are the 3 types of Potential Energy? (there r 4 actually but we only need the 3)

Answer 13

Gravitational Potential Energy
- Energy which is in position to object’s position relative to a certain
height.

Elastic Potential Energy
- Energy that is stored in an elastic
materials (stretched/compressed).

Chemical Potential Energy
- Energy that is inherent in all
substances like petrol, wood, and
plants.

Question 14

What is the formula used for Ug or Gravitational Potential Energy?

Answer 14

Ug = mgh

m - ass
g - ravity
h - eight

Question 15

What is the formula used to calculate EPE? (Elastic Potential Energy)

Answer 15

EPE = (1/2)kx^2

U = Elastic Potential Energy
k = Spring constant in Nm
x = displacement from equilibrium position

note: F = kx

Question 16

What does the Law of Conservation of Mechanical Energy state?

Answer 16

“Energy can neither be created nor be destroyed; it can only be internally converted from one form to another.”

Question 17

What is the Formula used for the Law of Conservation of Mechanical Energy?

Answer 17

KEi + PEi = KEf + PEf

(1/2)(m)(Vi)^2 + mgh = (1/2)(m)(Vf)^2 + mgh