P2.1 + 2 Forces and Their Effects + Kinetic Energy

Question 1

What factors affect thinking distance?

Answer 1

Drugs e.g caffeine and alcohol

Tiredness

Question 2

What is the thinking distance?

Answer 2

The distance the vehicle travels under the driver’s reaction time.

Question 3

What effect does the size of the parachute have on terminal velocity?

Answer 3

Bigger parachute = bigger resistance = faster time to reach terminal velocity = slower terminal velocity

Question 4

What is the breaking distance?

Answer 4

The distance a vehicle travels under the breaking force.

Question 5

What affects the breaking distance?

Answer 5

• Speed
• Condition of brakes
• Condition of tyres
• Grip (weather, road surface)

Question 6

What is momentum?

Answer 6

A property of moving objects

Question 7

What is the relationship between

mass + velocity and momentum?

Answer 7

+ mass = + momentum

+ velocity = + momentum

Question 8

What is the law of conservation of momentum?

Answer 8

In a closed system (no outside forces) the total momentum is the same before an event as after it.

Question 9

Describe terminal velocity

Answer 9

• Forces unbalanced (gravity > frictional force)
• Causes acceleration
• Speed increases = More particles/second hit = resistance increases
• The amount of speed = the amount of resistance eventually
• Constant speed in the same direction means terminal velocity has been reached

Question 10

What is the relationship between force and momentum?

Answer 10

A force acting on an object causes a change in momentum.
increased force = faster momentum change =
increased acceleration

Question 11

Explain a car’s safety features using momentum.

Answer 11

They slow down people over a longer time - a slower change in momentum means a smaller force acting on them and less damage.

Question 12

What is an elastic object?

Answer 12

An object that can return to its original shape after the force that changed it is removed.

Question 13

How does an elastic object go back to its original shape?

Answer 13

• Work is done (kinetic energy transferred) to an elastic to change its shape.
• This is stored as elastic energy in the object.
• After the force is removed, this is converted back into kinetic energy
• The object uses this to return to its original shape.

Question 14

What is the relationship between the load and spring extension?

Answer 14

They are directionally proportional up to the limit of proportionality.

Question 15

What is the limit of proportionality?

Answer 15

The maximum force an elastic object can take and still extend proportionally.

Question 16

What is velocity?

Answer 16

Speed in a given direction.

Question 17

How do you calculate distance from a velocity graph?

Answer 17

The area under the graph.

Question 18

What does acceleration, steady speed and deceleration look like on a velocity graph?

Answer 18

/ = acceleration

curved / = increasing acceleration

\ = deceleration

curved \ = decreasing acceleration

— = steady speed

Question 19

What does acceleration, steady speed, stop and deceleration look like on a distance time graph?

Answer 19

/ = steady speed

steepening curve / = acceleration

levelling off curve / = deceleration

— = stopped

Question 20

How is resultant force calculated?

Answer 20

Forces in the same direction are added
Forces in opposite directions are subtracted.
Whichever distance has the greatest force is the one the object moves in.

Question 21

What happens when there is a zero resultant force?

Answer 21

Equilibrium.

The object does not accelerate - if already moving than carries on at the same speed or if still doesn’t move.

Question 22

What does a non zero resultant force mean?

Answer 22

The object will accelerate.

Question 23

What is the rule of forces for when two objects interact?

Answer 23

For every force exerted there is an equal and opposite one.