FORCES #2

Question 1

what is newtons first law

Answer 1

if the resultant force on astationary object is zero the object will remain stationary. if the resultant force on a moving object is zero itll carry on moving at the same velocity

Question 2

the larger the resultant force on a object…

Answer 2

the more the object accelerates

Question 3

force and acceleration are …..

Answer 3

directly proportional

Question 4

equation for newtons second law

Answer 4

f=ma

Question 5

what is inertia

Answer 5

inertia is the tendency for motion to remain unchanged

Question 6

what is newtons third law

Answer 6

when two objects interact the forces they exert on each other are equal and opposite

Question 7

how do you find inertia mass

Answer 7

m=f/a

Question 8

example of newtons third law

Answer 8

is a man pushing against a wall
as he pushes against the wall there is a normal contact force acting back on him
the two forces are the same size
as the man applies a force and pushes the wall the wall pushes back on him with equal force

Question 9

stopping distance =

Answer 9

thinking distance + braking distance

Question 10

what is thinking distance

Answer 10

is how far the car travels during the drivers reaction time

Question 11

what is braking distance

Answer 11

is the distance taken to stop under the braking force

Question 12

what is thinking distance affected by

Answer 12

your speed, the fast you’re going the further youll travel
reaction time,
the longer your reaction time the longer your thinking distance

Question 13

what is braking distance affected by

Answer 13

your speed
theweather
condition of your tyres

Question 14

the larger the braking force

Answer 14

the larger the deceleration

Question 15

what can reaction time be affected by

Answer 15

tiredness
drugs
alcohol

Question 16

how can you measure reaction time

Answer 16

ruler drop test

Question 17

as a car speeds up….

Answer 17

thinking distance increases at the same rate

Question 18

braking distance increseases ….

Answer 18

faster the more you speed up

Question 19

momentum=

Answer 19

mass * velocity

Question 20

the greater the mass of an object or the greater its velocity….

Answer 20

the more momentum it has

Question 21

momentum before =

Answer 21

momentum after

Question 22

what is the conservation of momentum

Answer 22

in a closed systek the total momentum before an event is the same as after the event

Question 23

describe how momentum has been conserved by a gun recoiling

Answer 23

before the gun fires a bullet the toral momentum is zero
when the bullet leaves the gun it has momentum in one direction
the gun moves backwards so it has momentum int he opposite direction
this measn that the total momentum after the bullet has fired is zero this means momentum has been conserved

Question 24

force = (momentum)

Answer 24

change in momentum/change in time

Question 25

a larger force means.....

Answer 25

faster change in momentum

Question 26

car safwty featues

Answer 26

crumple zoens crumple on impact increasing the time taken for the car to stop seatbelts slightly increasing the time taken for the weare to stop air bags inflate before you hit the dashboard of a car

Question 27

how are bike helmets designed to reduce the impact of a fall (talk about momentum and time)

Answer 27

contain a crushable layer of foam which helps to lengthen the time taken for your head to stop in a crash which means there is a longer change in momentum

Question 28

how are crash mats designed to reduce the impact of a fall (talk about momentum and time)

Answer 28

they increase the time taken for you to stop if you fall on them which means there is a longer change in momentum

Question 29

why are cars designed to slow people down over a longer time when peole crash

Answer 29

the longer the takes for a change in momentum the smaller the rate of change of momentum so the smaller the force less force means less servere injury

Question 30

the longer the time taken for a change in momentum

Answer 30

the smaller the force

Question 31

a larger force or a larger distance means..

Answer 31

a larger moment

Question 32

what does it mean when an object has been elastically deformed

Answer 32

can go back to original shape or length

Question 33

what does it mean when an object has been in elastically deformed

Answer 33

doesn't return to original shape or length

Question 34

why do we need to push at right angles

Answer 34

because pushing at any other angle means a smaller distance, and so that means a smaller moment

Question 35

a force transmitted to a larger gear...

Answer 35

will cause a bigger moment, as the distance to the pivot is greater

Question 36

the pressure of a fluid means...

Answer 36

A FORCE IS EXERTED AT RIGHT ANGLES TO ANY SURFACE IN CONTACT WITH A FLUID

Question 37

what do objects in fluids experience

Answer 37

upthrust

Question 38

pressure increases with...

Answer 38

depth

Question 39

an object floats if its weight =

Answer 39

upthrust

Question 40

how do submarines use upthrust

Answer 40

to sink, large tanks are filled with water to increase the weight of the submarine so that it is more than the upthrust to go to the surface the tanks are filled with water to increase the weight of the submarine so that it will be more than the upthrust

Question 41

atmospheric pressure decreases with...

Answer 41

height

Question 42

how Is atmospheric pressure created

Answer 42

on a surface by air molecules colliding with the surface

Question 43

what is velocity

Answer 43

speed in a given direction

Question 44

why when the altitude increases does the atmospheric pressure decrease

Answer 44

because as the altitude increases the atmosphere gets less dense so there are fewer air molecules that are able to collide with the surface

Question 45

measuring displacement

Answer 45

displacement measures the distance and direction in a straight line from an objects starting and finishing point

Question 46

example of measuring displacement

Answer 46

if you walk 5m north then 5m south the displacement is 0m as its in a straight line the total distance is 10m

Question 47

Mark walks her dog after skl she takes a route of 1500m that starts and returns to her home what is the distance she travels whats her displacement

Answer 47

``` distance= 1500m displacement = 0m ```

Question 48

``` typical every day speeds walking running cycling car train plane ```

Answer 48

``` walking- 1.5m/s running- 3m/s cycling- 6m/s car- 25m/s train- 55m/s plane- 250m/s ```

Question 49

what is the number for acceleration due to gravity(falling object)

Answer 49

9.8m/s2

Question 50

when calculating uniform acceleration of a ball dropping what do you use for the acceleration

Answer 50

9.8m/s2

Question 51

how do you find the acceleration at a point on a velocity time graph

Answer 51

use a tangent to the curve at a point

Question 52

what is drag

Answer 52

resistance you get in a fluid, gas. or liquid

Question 53

how do you reduce drag

Answer 53

make the object stream lined

Question 54

example of drag

Answer 54

air resistance