Chapter 2

Question 1

Newton’s First Law of Motion

Answer 1

If no external forces are acting on it, and object will remain in its current state of motion forever

Question 2

Newton’s Second Law of Motion

Answer 2

Force=mass x acceleration

Question 3

Newton’s Third Law of Motion

Answer 3

To every action there is an equal and opposite reaction

Question 4

Describe terminal velocity

Answer 4

When an object falls it accelerates at a decreasing rate due to air resistance, until it reaches a speed at which it stops accelerating as air resistance and gravitational force balance. This speed is terminal velocity.

Question 5

Acceleration =

Answer 5

accceleration = change in velocity/time

Question 6

Momentum =

Answer 6

momentum = mass x velocity

Question 7

Resultant force =

Answer 7

resultant force = change in momentum/time

Question 8

causes of a change in momentum

Answer 8

change in speed
change in direction
change in mass

Question 9

causes of an increase in centripetal force

Answer 9

radius decreases
speed increases
mass increases

Question 10

causes of a decrease in centripetal force

Answer 10

radius increases
speed decreases
mass decreases

Question 11

define the Newton

Answer 11

1 Newton is the force required to give an object of mass 1kg an acceleration of 1m/s/s

Question 12

define resultant force

Answer 12

A resultant force is one force that has the same effect on an object as all the other individual forces that act on it combined

Question 13

effects of forces

Answer 13

forces can affect the motion, shape and/or volume of an object

Question 14

Two types of friction

Answer 14

Static and dynamic (static is greater than dynamic)

Question 15

Where does friction occur?

Answer 15

When two solids rub against eachother (the friction depends on how well the surfaces grip eachother)
When a fluid is pushed out of the way of a moving solid (the amount of friction depends on the objects velocity,, shape, surface area and the viscosity of the fluid)

Question 16

What is air resistance?

Answer 16

friction between a solid and a gas

Question 17

Effects of dynamic friction

Answer 17

• changes an objects kinetic energy into thermal energy
• ( so the object heats up)
• frictional heating causes small pieces of material to burn up, causing a streak of light known as a ‘shooting star’.

Question 18

weight =

Answer 18

weight = mass x g

Question 19

deceleration

Answer 19

negative acceleration

Question 20

finding speed

Answer 20

• from an equation: speed = distance/time
• from a distance-time graph: speed = gradient (change in y/change in x)
• average speed from a distance-time graph = total distance/total time

Question 21

finding acceleration from a speed-time graph

Answer 21

On a speed-time graph the acceleration is numerically equal to the gradient.

Question 22

define inertia

Answer 22

inertia is the tendency of objects to resist a change in their state of motion. Inertia can only be overcome by a force inn accordance with Newton’s First Law of Motion.

Question 23

How an object falls in a uniform gravitational field

Answer 23

• without air resistance, all subjects would fall at the acceleration of free fall, g
• with air resistance, the object would fall at a decreasing rate of acceleration, starting from g, until reaching terminal velocity

Question 24

difference between mass and weight

Answer 24

mass = amount of matter in a substance
weight = mass x g

Question 25

impulse =

Answer 25

impulse = force x time

Question 26

law of conservation of momentum

Answer 26

For a collision occurring between object 1 and object 2 in an isolated system, the total momentum of the two objects before the collision is equal to the total momentum of the two objects after the collision. That is, the momentum lost by object 1 is equal to the momentum gained by object 2.