⭐️Topic SP2 - Motion And Forces

Question 1

What is acceleration?

Answer 1

How much velocity changes in a certain time

Question 2

How do you work out the resultant force of two forces on an object?

Answer 2

You add them if in the same direction or subtract them if opposite direction

Question 3

What does Newton’s first law state?

Answer 3

A moving object will continue to move at the same speed and direction unless acted upon by an external force
Or
An object in motion stays in motion unless acted upon by an external force

Question 4

What is centripetal force?

Answer 4

The resultant force that causes an object to change direction - so it moves in a circular path

Question 5

Give examples of centripetal force?

Answer 5

Friction, tension (e.g. wires of a fairground ride) and gravity

Question 6

What is mass? When does it change?

Answer 6

The amount of matter there is in an object. It only changes when the object itself changes

Question 7

What is weight?

Answer 7

A measure of the pull of gravity there is on an object

Question 8

What device can be used to measure weight?

Answer 8

A force meter as they have a spring which stretches as the force on it increases

Question 9

What is gravitational field strength in earth?

Answer 9

9.8 N/kg but in calculations can be rounded to 10N/kg

Question 10

How can you calculate weight?

Answer 10

Weight (N) = mass (kg) x gravitational field strength (N/kg)

Question 11

What is Newton’s 2nd law?

Answer 11

Force N = mass kg x acceleration m/s squared

Question 12

What is the inertial mass of an object?

Answer 12

The force on the object / the acceleration produced by the force

Question 13

What’s Newton’s third law?

Answer 13

Action reaction forces

Question 14

Give characteristics of a pair of action reaction forces

Answer 14

They both are the same size
both act in opposite directions
They are the same type of force

Question 15

What’s the difference between action reaction forces and balanced forces?

Answer 15

Action reaction forces act on different objects but balanced forces all act on the same object

Question 16

What is momentum?

Answer 16

A measure in the tendency of an object to keep moving or how hard it is to stop it moving

Question 17

Is momentum a vector or scalar?

Answer 17

Vector

Question 18

How do you calculate momentum?

Answer 18

Momentum (kg m/s)= mass (kg) x velocity (m/s)

Question 19

How can momentum and acceleration be combined in a formula?

Answer 19

F = m(v-u) / t

Question 20

What is the rule for conservation of momentum?

Answer 20

When moving objects collide, total momentum of both objects is the same before the collision as it is after the collision as long as no external forces are acting upon it

Question 21

What’s thinking distance?

Answer 21

The distance traveled by a driver while reacting to a situation

Question 22

What’s breaking distance?

Answer 22

The distance travelled by the vehicle while the breaks are working to stop it

Question 23

What’s stopping distance equal to?

Answer 23

Thinking distance + breaking distance

Question 24

What is a reaction time?

Answer 24

The time between the person detecting their stimulus and their response

Question 25

What can be used to measure response times?

Answer 25

Using computers or electric circuits

Question 26

What’s the typical reaction time to a visual stimulus?

Answer 26

0.25 seconds

Question 27

What increases reaction time?

Answer 27

By being under influence of drugs, alcohol or dit reactions like using your phone

Question 28

What may increase the breaking distance?

Answer 28

By having worn out breaks as less friction is created, if the road is wet or there’s loose gravel as friction is reduced, if the tyres are worn out as friction is reduced, if the vehicle has a larger mass as more force is needed to decelerate it

Question 29

Why is overall stopping distance for cars less than lorries

Answer 29

As cars will automatically have a smaller breaking distance as they have a lower mass

Question 30

What is the formula for work done?

Answer 30

Work down (J) = force (N) x distance moved in the direction of the force (m)

Question 31

What’s the formula for kinetic energy?

Answer 31

KE = 1/2 x mass (kg) x speed squared (m/s^2 )

Question 32

What is a deceleration?

Answer 32

A negative acceleration

Question 33

How do crumple zones on cars reduce forces on occupants in a collision?

Answer 33

as they take a little time for the crumpling on the car to happen in a collision so the deceleration of the car is less and the force of the car is also reduced

Question 34

How do seat belts reduce forces on occupants in a collision?

Answer 34

They hold passengers into the car so the effect of the crumple zone reduces the forces on the passenger as well as the car

Question 35

How do air bags help reduce forces on occupants in a collision?

Answer 35

They increase the time it takes for a person’s head to stop in a collision

Question 36

How can you calculate the force in terms of change in momentum?

Answer 36

F = mass x v - mass x u / t