Forces, movement, shape and momentum

Question 1

What effect does a force have on an object?

Answer 1

• Changes object’s speed
• Changes object’s direction
• Changes object’s shape

Question 2

List the different types of forces?

Answer 2

• Gravitational
• Electrostatic
• Weight
• Normal reaction
• Friction
• Air resistance
• Upthrust
• Nuclear
• Magnetic

Question 3

What is the difference between scalar and vector?

Answer 3

• Scalar - magnitude only
• Vector - magnitude and direction

Question 4

name 6 vector quantities?

Answer 4

There are only 6 vector quantities (assume everything else is scalar!)

• Displacement
• Velocity
• Acceleration
• Force
• Weight
• Momentum

Question 5

What is Newton’s 1st Law?

Answer 5

• If forces acting on an object are balanced, the resultant force is zero
• Object at rest, stays stationary
• Object moving, continues to move in same direction and at same speed

Question 6

What is Newton’s 2nd Law?

Answer 6

• Acceleration is proportional to resultant force
• Inversely proportional to mass of object

Question 7

How to calculate resultant force acting along a line

Answer 7

Add up all forces acting in useful direction
- Subtract all forces acting in the opposite direction

Question 8

equation for force, mass and acceleration?

Answer 8

Force = mass x acceleration
F = m x a

Question 9

equation for Weight , mass, and ravitational field strength

Answer 9

Weight = mass x gravitational field strength
W = m x g

Question 10

equation for stopping distance?

Answer 10

Stopping distance = thinking distance + braking distance

Question 11

Define stopping distance

Answer 11

• The distance travelled by a vehicle after a hazard has been spotted until it comes to a
  complete rest
• Stopping distance = thinking distance + braking distance

Question 12

What factors affect braking distance?

Answer 12

• Speed vehicle is travelling
• Mass of vehicle
• Condition of road
• Tyres and brakes

Question 13

How is braking distance increased?

Answer 13

• If vehicle is travelling at higher speed
• Worn brakes
• Icy road

Question 14

What factors affect thinking distance?

Answer 14

• Reaction time
• Tiredness
• Drink and drugs

Question 15

How is thinking distance increased?

Answer 15

• Tiredness
• Driving under the influence of drink and drugs

Question 16

Describe the process of terminal velocity

Answer 16

• Weight acts downwards
• Drag acts upwards
• Object accelerates downwards
• Eventually weight = drag
• No resultant force, no acceleration, forces are balanced
• Terminal velocity (constant velocity) is reached

Question 17

What is Hooke’s law?

Answer 17

• The extension of a spring is directly proportional to the force applied, provided its limit
  of proportionality is not exceeded

Question 18

Define elastic behaviour

Answer 18

• The ability of a material to revert to its original shape after the forces causing deformation
  have been removed

Question 19

What happens if elastic limit is exceeded?

Answer 19

• Material will no longer revert to original shape after the forces have been removed

Question 20

What is the equation for momentum?

Answer 20

• Momentum = mass x velocity
  p = m x v

Question 21

What is the unit of momentum?

Answer 21

• kg m/s

Question 22

Explain how seat belts/crumple zones/air bags prevent serious injury

Answer 22

• Same momentum change
• But time of impact increases
• Reducing force felt
• Seat belt stretches increasing area over which force acts
• Pressure on body reduces

Question 23

When 2 vehicles collide what happens

Answer 23

• They exert equal and opposite forces on each other
• Their total momentum is unchanged

Question 24

equation for force, change in momentum and time?

Answer 24

Force = change in momentum
Time
F = (mv - mu)
t

Question 25

What is Newton’s 3rd Law?

Answer 25

• Two objects exert equal and opposite forces on each other

Question 26

What is a moment?

Answer 26

• The turning effect of a force

Question 27

equation for moment?

Answer 27

Moment = force x perpendicular distance from pivot

Question 28

How do you increase the moment of a force?

Answer 28

• Increase distance
• Increase force

Question 29

Define ‘centre of mass’

Answer 29

The point where the mass appears to be concentrated