Forces and Motion

Question 1

Speed=

Answer 1

Distance/Time

Question 2

Acceleration=

Answer 2

Change in Velocity/Time

Question 3

What is the force of attraction between all masses?

Answer 3

Gravity

Question 4

Weight=

Answer 4

Mass x Gravitational Field Strength

Question 5

What is friction?

Answer 5

A force which opposes motion

Question 6

What do things need to travel at a steady speed?

Answer 6

A driving force to counteract the friction

Question 7

How can you reduce friction between solid surfaces that are sliding past each other?

Answer 7

Use of lubricant like oil or grease

Question 8

The higher the drag…

Answer 8

The lower the speed

Question 9

In a fluid, friction always increases as…

Answer 9

the speed increases

Question 10

What will all free falling things reach?

Answer 10

Terminal Velocity

Question 11

What does drag depend on?

Answer 11

Shape and area

Question 12

How does terminal velocity occur?

Answer 12

When a free falling object first sets off they have much more force accelerating than resistance slowing them down.
As the velocity increases, the resistance builds up
This gradually reduces the acceleration until eventually the resistance force is equal to the accelerating force = terminal velocity

Question 13

What’s an investigation you can use for free fall?

Answer 13

Sycamore seeds

as there have a small weight and large surface area, making easy to investigate

Question 14

What is the first law of motion?

Answer 14

Balanced forces mean no change in velocity

Question 15

What is Newton’s second law of motion?

Answer 15

If there is an unbalanced force, then the object will accelerate in that direction

Question 16

What is the unbalanced force often called?

Answer 16

Resultant force

Question 17

What is the third law of motion?

Answer 17

If object A exerts a force on object B, then object B exerts the exact opposite force on object A

Question 18

The distance it takes to stop a car is divided into…

Answer 18

Thinking distance and braking distance

Question 19

What is thinking distance affected by?

Answer 19

Tiredness, Drugs, alcohol, old age

Question 20

What factors is braking distance affected by?

Answer 20

How fast your going
Mass of vehicle
How good your brakes are
Road surface, weather conditions and tyre (affect grip)

Question 21

What is a moment?

Answer 21

The turning affect of a force

Question 22

Moment=

Answer 22

Force(N) x perpendicular distance from pivot

Question 23

How do you get the maximum moment on a spanner?

Answer 23

by pushing at right angles
using a longer spanner
larger force

Question 24

Where does the centre of gravity hang?

Answer 24

Directly below the point of suspension

Question 25

What does Hooke's law say?

Answer 25

Extension is proportional to force

Question 26

The length of an unstretched metal wire is called...

Answer 26

it's natural length

Question 27

When does Hooke's law stop working?

Answer 27

When you increase the force past elastic limit

Question 28

A galaxy is a collection of...

Answer 28

billions of stars

Question 29

The universe is a large collection of...

Answer 29

billions of galaxies

Question 30

What force causes orbits?

Answer 30

gravity

Question 31

The moon orbits

Answer 31

the earth

Question 32

What are comets?

Answer 32

small lumps of icy rock that orbit the sun

Question 33

What is the orbit of a comet like?

Answer 33

elliptical, with the sun at one focus | faster nearer the sun

Question 34

What is the third law of motion?

Answer 34

If object A exerts a force on object B then object B exerts the exact opposite force in object A

Question 35

What do you need to know, to know the resultant force?

Answer 35

the size of all the different forces acting on the object and their direction

Question 36

What quantity is force?

Answer 36

a vector quantity

Question 37

What do vector quantities have?

Answer 37

a size and a direction

Question 38

Name some vector quantities

Answer 38

``` force velocity displacement acceleration momentum ```

Question 39

What are quantities that only have size and no direction called?

Answer 39

scalar quantities

Question 40

Give some examples of scalar quantities

Answer 40

Mass Temperature Time Length

Question 41

Momentum =

Answer 41

Mass x Velocity

Question 42

The greater the mass of an object...

Answer 42

The greater it's velocity and the more momentum it has

Question 43

What happens to momentum when no external forces act?

Answer 43

Momentum is conserved

Question 44

Force acting (N) =

Answer 44

Change in momentum / Time taken for change to happen

Question 45

What happens when a force acts on an object?

Answer 45

It causes a change in momentum

Question 46

What does the crumple zones on cars do?

Answer 46

They crumple on impact, increasing the time taken for the car to stop

Question 47

What do seat belts do?

Answer 47

They stretch slightly, increasing the time taken for the wearer to stop. This reduced the forces acting on the chest.

Question 48

What three things do cars have to slow people down over a longer time when they have a crash?

Answer 48

Crumple Zones Seat belts Air Bags

Question 49

If an object is balanced, what is the equation?

Answer 49

Total anticlockwise moments = Total clockwise moments

Question 50

What happens if the total anticlockwise moments do not equal the total clockwise moments?

Answer 50

There will be a resultant moment