Forces

Question 1

What is a force?

Answer 1

> It is a push or Pull factor, that acts on an object due to its interaction with another object.

Question 2

What is a contact force and give some examples?

Answer 2

> Requires two objects to be touching.
E.g. Friction, air resistance, Tension

Question 3

What is a non-contact force and give some examples?

Answer 3

> Doesn’t require objects to be touching.
E.g. Gravitational, electrostatic, magnetic

Question 4

What is a scalar quantity with examples?

Answer 4

> Have only magnitude
E.g. speed, mass, distance, temperature, time

Question 5

What is a vector quantity with examples?

Answer 5

> It has magnitude and direction
E.g. Displacement,momentum,velocity,ecceleration,force

Question 6

What is the resultant force?

Answer 6

> Resultant Force=Overall force on an object
Equilibrium is all forces=0

Question 7

What is Elastic deformation

Answer 7

When an object returns to its original shape.

Question 8

What is inelastic deformation?

Answer 8

> When an objects stays deformed.

Question 9

What is Extension?

Answer 9

Increase in length of a spring when its stretched.

Question 10

What is the formula which involved Force,spring and extension?

Answer 10

F=Ke
Force = Spring X Extension
(N) (N/m) (M)

Question 11

What is Hooke’s Law?

Answer 11

Force is Directly Proportional to Extension

Question 12

How do you workout Elastic Potential Energy?

Answer 12

Ee = 0.5 k e^2
Elastic Potential Energy = 0.5 X Sprung constant X Extension^2

Question 13

Describe a method used to investigate the stretching of a Spring?

Answer 13

• Set up a clamp stand with a clam and hang the spring from the clamp
  *Use a second clamp and boss to fix a (half) metre rule alongside the spring
  *Record the ruler reading that is level with the bottom of the spring
  *Hang a 1 N / a known weight from the bottom of the spring
  *Record the new position of the bottom of the spring
  *Calculate the extension of the spring and measure the extension of the spring
  *Add further weights to the spring so the force increases 1 N at a
  time up to 5 N

Question 14

Formula to workout velocity?

Answer 14

Displacement
Velocity = ————————-
Time Taken

Question 15

Typical Everyday speeds?

Answer 15

Walking=1.5 m/s
Cycling=6 m/s
Running=3 m/s
Train=5 m/s
Car=25 m/s
Train=55 m/s

Question 16

What is acceleration?

Answer 16

> Rate of change in velocity.
(How quickly something speeds up/slows down).

Question 17

What is the equation for acceleration?

Answer 17

. . . Change in Velocity (m/s)
Acceleration= ————————————–
Time (s)

Question 18

What is the equation for acceleration?

Answer 18

2as= v’2-u’2

2(Acceleration + Distance) = Final V - Initial V

Question 19

Describe the terminal velocity of objects falling?

Answer 19

> At the start when they fall off, the force of gravity is much more than the frictional force, so they accelerate.
As the speed increases friction builds up
This gradually decreases the acceleration until eventually the frictional force is equal to the accelerating force
It will have reached it’s maximum speed

Question 20

Describe the terminal velocity of a skydiver falling?

Answer 20

> Initially, the upwards air resistance is very small because the skydiver isn’t falling very quickly
As they speed up, the air resistance increases, eventually growing large enough to balance the downwards weight force
Once air resistance equals weight, there is no longer any resultant force
Therefore, the skydiver’s acceleration is zero - they now travel at a constant speed
This speed is called their terminal velocity

Question 21

What is Newton’s First Law of Motion?

Answer 21

> ‘If the resultant force of a stationery object = 0, the object will remain stationery.
If the resultant force of a moving object is 0 then it will carry on moving at the same velocity’.

Question 22

What is Newton’s second law of motion?

Answer 22

‘The larger the resultant force acting on an object, the more the object accelerates’.

Question 23

What is the formula to workout force?

Answer 23

F=MA
Force= Mass X Acceleration

Question 24

What is Inertia?

Answer 24

> The tendency for the motion of an object to remain unchanged.

Question 25

What is Newton’s Third law of motion?

Answer 25

‘When two objects, the forces they exert on each other are equal and opposite’.

Question 26

Memorise Required Practical

Answer 26

Acceleration one…..

Question 27

What is the stopping distances?

Answer 27

> Minimum distance required to stop a vehicle in an emergency.

Question 28

What is the formula to workout stopping distance?

Answer 28

Stopping Distance= Thinking + Braking Distance

Question 29

What is the thinking distance?

Answer 29

> How far the car travels during the driver’s reaction time.

Question 30

What is the Braking distance?

Answer 30

> The distance taken to stop under the breaking distance.

Question 31

What are factors affecting thinking distance?

Answer 31

> Speed, the faster the further you’ll travel,
Reaction time which varies between people.
Tired, drunk, drugs , distractions

Question 32

What are factors affecting Braking distance?

Answer 32

> Speed, faster it travels longer it takes to stop
Weather or road surface
The condition of the tyres
The condition of brakes.

Question 33

Explain what happened when you push the brakes.

Answer 33

> When the brake activates it presses against the wheel
Force of friction now acts between the break
Kinetic energy is converted in thermal energy, so the temperature of the brakes increases.
At the same time car slows down as it loses kinetic energy
the greater the speed the greater the braking force.

Question 34

What is the formula for momentum?

Answer 34

Momentum=Mass X Velocity

(Kg m/s) = M x m/s

Question 35

What is the conservation of momentum?

Answer 35

> In a closed system, the total momentum before an event is equal to the total momentum after an event,
So momentum is conserved.