Forces

Question 1

what are forces

Answer 1

pushes or pulls

Question 2

Forces can :

Answer 2

change the size or shape of an object
change the speed things are moving (make them faster or slower)
change the direction of a moving object

Question 3

what is the unit for measuring forces

Answer 3

newton (N)

Question 4

what are contact forces

Answer 4

a force that acts at the point of contact between two objects

Question 5

what do contact forces need to do

Answer 5

need to tough the thing that they are affecting

Question 6

examples of contact forces

Answer 6

friction, air resistance, water resistance, upthrust

Question 7

what are non-contact forces

Answer 7

forces that don’t need to tough the ting that they are affecting

Question 8

examples of no-contact forces

Answer 8

magnetism, gravity, static electricity

Question 9

example of balanced forces

Answer 9

if the upwards and downwards forces on a balloon are balanced. the balloon will not move.
the upwards force- upthrust and the downwards force- force from the string are balanced

Question 10

why doesn’t a rocket in space need to use its engine to keep moving.

Answer 10

because there is no air in space, so there is no air resistance to slow it down.

Question 11

example of balanced forces in water

Answer 11

if you are floating in a swimming pool, your weight and upthrust are balanced

Question 12

how can you decide if something is floating

Answer 12

by working out its density

Question 13

what is density

Answer 13

the mass of a certain volume of something

Question 14

how can density be calculated

Answer 14

density = mass divided by volume

Question 15

unit for density

Answer 15

g/cm3

Question 16

density of water

Answer 16

1g/cm3

Question 17

when will an object sink or float

Answer 17

if an object has a density less than 1g/cm3it will float

if the density is greater than 1g/cm3 it will sink

Question 18

how will elastic materials stretch with a force

Answer 18

stretch with a force and then return to their original shape when the force is taken away

Question 19

how will plasticise materials stretch with a force

Answer 19

will stretch with a force but they will not return to their original shape afterwards

Question 20

what is used to measure a force and why

Answer 20

a force meter, because they have springs in them that are elastic

Question 21

what is mass

Answer 21

the amount of substance in your body

Question 22

what is mass measured in

Answer 22

kilograms (kg)

Question 23

what is the weight

Answer 23

a force caused by gravity pulling on your body

Question 24

what will change/remain when you move an object

Answer 24

its mass will not change but its weight depends on the force of gravity

Question 25

weight difference between earth and moon

Answer 25

an object on the moon would have a smaller weight than on earth, because the moons gravity is not as strong as earths

Question 26

what does gravity pull on every kilogram with

Answer 26

a force of 10N

Question 27

what is friction

Answer 27

a forced caused by two things rubbing together

Question 28

types of friction

Answer 28

air resistance and water resistance sometime called drag

Question 29

friction can :

Answer 29

slow things down, wear things away, produce heat, make an noise

Question 30

when is friction helpful

Answer 30

your shoes grip the floor tyres and brakes use friction pencils write because of friction

Question 31

when is friction not helpful

Answer 31

parts of engine wear away | makes bicycles harder to pedal

Question 32

how can friction be increased

Answer 32

by using rough surfaces or by using materials like rubber that have a lot of friction

Question 33

how can friction be decreased

Answer 33

by using smooth surfaces or by lubrication like oil and grease.

Question 34

how do you work out speed

Answer 34

distance travelled divided by time taken

Question 35

what is the thinking distance

Answer 35

the distance the car travels while the driver is deciding to stop

Question 36

what is the braking distance

Answer 36

the distance it travels while it is slowing down

Question 37

how do you get the stopping distance

Answer 37

thinking distance + braking distance

Question 38

when are stopping distances longer

Answer 38

if the road is wet or icy, if the car has worn tyres, if the driver is tired or been drinking alcohol

Question 39

how can a journey be shown

Answer 39

on a distance/ time graph

Question 40

when a person runs what will it look like on a graph

Answer 40

steep increase

Question 41

if a person stops what will it look like on a graph

Answer 41

a straight line

Question 42

when a person walks slowly what will it look like on a graph

Answer 42

steady increase

Question 43

the steeper the line on the graph .....

Answer 43

the faster they are moving