P10 - Force And Motion✔️

Question 1

Equation for resultant force?

Answer 1

Resultant force = mass x acceleration

F = m x a

Question 2

What does Newtons second law state?

Answer 2

States that the acceleration of an object is poportional to the resultant force on the object and inversley proportional to the mass of the object

Question 3

What is inertia?

Answer 3

Inertia is the tendency of an object to stay at rest or continue in uniform motion

-can be defined as: force / aceleration

Question 4

What is the inertia mass of an object?

Answer 4

Is a measure of the difficulty of changing the objects velocity

Question 5

Greater resultant force on a object ……?

Answer 5

The greater the objects acceleration

Question 6

The greater the mass of an object ……?

Answer 6

The smaller its acceleration for a given force

Question 7

What is weight?

Answer 7

Weight - weight of an object is the force acting on it due to gravity measured in newtons,N

Question 8

What is mass?

Answer 8

Mass of an object depends on the quantity of matter in it - measured in kilograms,kg

Question 9

What is gravitational field strength?

Answer 9

Way of measuring how much gravity there is at a single point - strength at earths surface is about 9.8 N/kg

Question 10

Equation for weight?

Answer 10

Weight = mass x gravitational field strength

W = m x g

Question 11

What is terminal velocity?

Answer 11

Steady speed achieved by an object freely falling through a gas or liquid - where the frictional force on it is equal to its weight - resultant force is 0

Question 12

What is the resultant force on an object moving at terminal velocity?

Answer 12

Resultant foce on the object is zero

Question 13

What is stopping distance?

Answer 13

The shortest distance in which a vehicle can safetly stop - it is the sum of thinking distance and braking distance

Question 14

What is thinking distance?

Answer 14

Distance traveld by a vehicle in the time it takes the driver to react - proportional to the speed

Question 15

What is breaking distance?

Answer 15

Distance travelled by a vehicle during the time the braking force acts

Question 16

Equation for stopping distance?

Answer 16

Stopping distance = thinking distance + breaking distance

Question 17

Factors affecting stopping distance?

Answer 17

-tirdness,acholl,drugs - increase reaction time because they affect the brain

-faster a vehicle is travelling - further it travels before its stops

-condition of vehicle - worn break/tires take longer to stop they are less effective

-conditions of enviorment - icy road less friction on tires

Question 18

What is momentum?

Answer 18

Momentum - vector quantity of motion that is made up of the amount of matter moved and the velocity at which it moves

Question 19

Equation of momentum?

Answer 19

Momentum of moving object = mass x velocity

P = m x v

Measure in kg/ms

Question 20

What is a closed system?

Answer 20

A system at which the total momentum before an event is the same as the total momentum after the event - called conservation of momentum

Question 21

Why does making the impact time longer reduce the imapact force?

Answer 21

If an object hits a soft wall, the wall would act as a cushion and increase the impact time so the momentum of the object would be reduced over a longer time and so the change of momentum per second would be less - longer impact time the more the impact force is reduced

Question 22

What determines the force of the impact when vehicles collide?

Answer 22

Depends on the mass,change in velocity and the length of the impact time

Question 23

What happens when two vehicles collide - refer to forces?

Answer 23

-They exert equal and opposite forces on each other

-their total momentum is unchanged

Question 24

Equation for impact force?

Answer 24

Impact force = change of momentum / impact time

Question 25

Why are safety helmets worn?

Answer 25

They increase the impact time which reduces the rate of which momentum changes per second - so they reduce impact forcce of the impact

Question 26

Why are seat belts worn?

Answer 26

-time taken to stop someone in the car is longer so the decelerating force is reduced

-seat belt spreads the force out across the chest

Question 27

What do air bags do?

Answer 27

Spreads the force of an impact across the upper part of a persons body it also increases the impact time so the efect of the force is reduced

Question 28

Three methods used to reduce impact time in cars?

Answer 28

-collapsible steering wheels
-crumple zones
-side impact bars

Question 29

Relationship between thinking distance and speed?

Answer 29

Thinking distance is proportional to speed

Question 30

Factors that effect human reaction time?

Answer 30

Drugs,alcohol and tiredness

Question 31

Define what an elastic object is?

Answer 31

An object is elastic if it returns to its original shape when the forces deforming it are removed

Question 32

What is extenstion?

Answer 32

Extenstion is the difference between the length of the object and its original length

Question 33

Define Hooke’s law?

Answer 33

Extenstion of a spring is directly proportional to the force applied to it, as long as the limit of proportionality is not exceeded.This relationship is linear

Question 34

Equation for hookes law?

Answer 34

Force applied (F) = spring constant (K) x extenstion (e)