Week 2

Question 1

Inertia

Answer 1

maintaining a state of motion

Question 2

force

Answer 2

any push or pull on an object

Question 3

net force

Answer 3

the combination of all the forces that act on an object

Question 4

mechanical equilibrium

Answer 4

when the net force is 0

Question 5

friction

Answer 5

a resisting force

Question 6

mass

Answer 6

quantity of matter in an object

Question 7

weight

Answer 7

the force on an object due to gravity

Question 8

momentum

Answer 8

inertia of motion (object resisting change to motion)

Question 9

impulse

Answer 9

change in momentum due to force and time

I = F x t

Question 10

work (w)

Answer 10

product of force (F) on an object and the distance (d) it is moved by the force
w = F x d

Question 11

power (P)

Answer 11

quantity of work (w) done per unit time (t)

P = w / t

Question 12

energy

Answer 12

ability to do work

Question 13

mechanical energy

Answer 13

energy due to an object’s movement and relative position

Question 14

potential energy

Answer 14

work (w) done on an object to put it in a new location relative to another location, the object stores that energy as ‘potential energy’
e.g stretching an elastic band

Question 15

kinetic energy

Answer 15

energy received from the thing that made it be in motion, while in motion an object holds kinetic energy
e.g when two objects collide

Question 16

center of mass

Answer 16

a point in the center of an object where its mass is concentrated.

Question 17

center of gravity

Answer 17

the point in the center of an object’s mass where the force of gravity is considered to act.

Question 18

stable equilibrium

Answer 18

the state of an object balanced so that any small displacement or rotation raises its center of gravity

Question 19

Differentiate between Static and Dynamic Equilibrium

Answer 19

Static: the object is still
Dynamic: the object is steadily moving

Question 20

Why is net force required for acceleration of an object?

Answer 20

A net force is required to move the object out of equilibrium

Question 21

Relate the magnitude of acceleration to the net force on and mass of an object

Answer 21

F = m x A, therefore A = F/m

Question 22

Differentiate between mass and weight

Answer 22

Mass is the amount of matter in an object, weight is the force of an object due to gravity

Question 23

Newton’s First Law of Motion

Answer 23

An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Question 24

Newton’s Second Law of Motion

Answer 24

The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.

Question 25

Newton’s Third Law of Motion

Answer 25

For every action, there is an equal and opposite reaction.

Question 26

Relate the magnitude of momentum of an object to its mass and velocity

Answer 26

Momentum = m x V,

Question 27

Relate impulse to force and the time over which the force is applied and to the magnitude of momentum change

Answer 27

The longer an object has a force applied to it, the greater the momentum.
Eg, a ball rolling down a hill for 20 seconds has a higher momentum than a ball rolling down a hill for 10 seconds.

Question 28

Apply the concept of impulse in discussing the control of momentum and force during time of contact of two objects

Answer 28

In an collision the impulse experienced by the object is always equal to the momentum change

Question 29

Relate work to force and the distance over which the force is applied

Answer 29

w = F x d 
work = force x distance

Question 30

explain how mechanical energy can be converted between potential and kinetic forms

Answer 30

Mechanical energy is converted between KE and PE as the mechanical energy sum is always the same

Question 31

State the law of conservation of energy

Answer 31

energy cannot be created or destroyed, but only changed from one form into another or transferred from one object to another.

Question 32

Relate the position of an object’s center of mass relative to its base of support to the object’s stability and stable equilibtrium

Answer 32

The closer the center of mass is to the center of base of support, the higher the stability

Question 33

SI units of Force, Mass, Energy and Power

Answer 33

Force: newtons
Mass: Kilograms
Energy: Joules
Power: Watt