Topic 2 Motion And Forces (complete)

Question 1

What is a scalar quantity

Answer 1

Has magnitude but no direction

Question 2

What is a vector quantity

Answer 2

Has magnitude and direction

Question 3

Which of these are vector/scalar Displacement/distance
Speed
velocity
Acceleration
Force
Weight
mass
Momentum
Energy

Answer 3

Displacement:vector
distance:scalar
Speed:scalar
velocity:vector
Acceleration:vector
Force:vector
Weight:vector
mass:scalar
Momentum:vector
Energy:scalar

Question 4

What is the difference between speed and velocity

Answer 4

Velocity is the same as speed except that velocity states a direction

Question 5

Speed=
Distance=
Time=

Answer 5

Speed=distance/time
Distance=speed*time
Time=distance/speed

Question 6

How do you calculate gradient of a line

Answer 6

y
—
x

Question 7

What does newtons 1st law state
(About resultant force)

Answer 7

If resultant force on an object is zero the object will stay stationary or keep moving at the same velocity

Question 8

What happens if the resultant force on an object is not zero

Answer 8

The speed or direction of the body changes

Question 9

What is the formula for Newton’s second law

Answer 9

Force = mass *acceleration
N Kg 2
m/s

Question 10

Explain how weight and mass are not the same

Answer 10

Mass is the amount of stuff inside an object but weight is the force of the object based on the gravity of the area it is in

Question 11

Weight=
Mass=
Gravitational field strength=

Answer 11

Weight=m*g
Mass=w/g
Gravitational field strength=w/m

Question 12

What is weight measured in?

Answer 12

Newtons
N

Question 13

What is gravitational field strength

Answer 13

The pull of gravity on that object
If the gravitational field strength is high the weight of the object will be high

Question 14

An object moving in circular motion at at the same speed has a changing velocity ,why?

Answer 14

Because velocity is vector with magnitude and direction and the speed is the same but the direction of the object is changing as it moves in circular motion

Question 15

If an object is moving in a circular motion what does this say about the resultant force

Answer 15

That there is a resultant force as the direction is always changing

Question 16

What is the force called of an object moving in circular motion

Answer 16

Centripetal force

Question 17

What does inertia mean

Answer 17

Tendency of an object to keep moving at constant velocity

Question 18

How can inertial mass be found in Newton’s second law

Answer 18

M=f/a
Inertial mass is the ratio of force over acceleration

Question 19

What does Newton’s third law state

Answer 19

When 2 objects interact they exert equal and opposite forces on each other

Question 20

When one car with a mass of 55kg hits another car with a mass of 65 kg what happens

Answer 20

They both collide and experience equal and opposite forces from each other but the car that weighs 55 kg will accelerate more than the heavier car because

Question 21

What is the formula for momentum

Answer 21

Momentum = mass >< velocity
Kg m/s Kg M/s

Question 22

A cheetah is running at 60m/s and weighs 50kg
What is its momentum

Answer 22

Momentum=mass><velocity><60
Momentum=3000 kg m/s</velocity>

Question 23

Total momentum before=Total momentum after

Question 24

A 1500kg car travelling at 25m/s crashes into back of parked car
Parked car has mass of 1000kg
2 cars lock together and move in same direction as original moving car
Calculate the velocity that the 2 cars move with

Answer 24

Momentum before collision
(1500kg><25m/s)+(1000kg+0m/s)
=37500 kg m/s
Total momentum before collision =total momentum after collision
37500=37500
New mass of cars =2500
Velocity=momentum/mass
Velocity=37500/2500
Velocity=15m/s

Question 25

Change in momentum/time =?

Answer 25

Change in momentum/time = Force

Question 26

Calculate force required to accelerate a 600g ball from rest to 14m/s in 0.1s

Answer 26

Change in momentum/time=force (0.6><14 - 0.6><0)/0.1=force (8.4 - 0)/0.1=force 84N=force

Question 27

Stopping distance = ?+?

Answer 27

Stopping distance = braking distance + thinking distance

Question 28

What are some typical results using ruler drop tests to measure reaction time

Answer 28

0.2-0.6 s

Question 29

Explain the ruler drop test to measure reaction time

Answer 29

Get someone to hang ruler between your thumb and forefinger lined up with the bottom of ruler They should let it go randomly without warning and the distance between the bottom of the ruler and where you held it is the reaction time Use equation acceleration = change in velocity/time

Question 30

What factors affect the stopping distance of a vehicle

Answer 30

Mass of vehicle Speed of vehicle Drivers reaction time State of vehicle brakes State of road Friction between tyre and road

Question 31

What factors affect a drivers reaction time

Answer 31

Tiredness alcohol drugs distractions

Question 32

Using equation force=change in momentum/time How does a large deceleration cause danger

Answer 32

Large decelerations mean there will be a higher force caused meaning the people in the vehicle will fell a high force which may injure them

Question 33

As speed increases the thinking distance increases at a constant rate but what about the braking distance

Answer 33

Braking distance increases at a much higher rate and have a squared relationship If speed doubles the braking distance jncreases by 4 if speed triples then the braking distance increases by 9

Question 34

1/2 >< mass >< v^2 = F >< D

Question 35

Final velocity ^2 -Initial velocity^2 = 2 >< acceleration >< distance

Question 36

What is the acceleration ,g, in free fall for everyday acceleration

Answer 36

10m/s^2

Question 37

How do you calculate acceleration using velocity time graph

Answer 37

Acceleration= (y)change in velocity/(x)change in time

Question 38

How do you calculate distance traveled on a velocity time graph

Answer 38

Calculate the area under the lines you are finding the distance travelled for

Question 39

What are the typical speeds for these Walking Running Cycling

Answer 39

Walking 1.4 m/s Running 3m/s Cycling 5.5 m/s

Question 40

Giga(G)-10^9 Mega(M)-10^6 Kilo(k)-1000 Centi(c)-0.01 Mili(m)-0.001 Micro(µ)-10^-6 Nano(n)-10^-9