Section 17

Question 1

Velocity

Answer 1

Is speed in a given direction

Question 2

Displacement

Answer 2

Measures the distance and direction in a straight line

Question 3

Speed, vectors and scalar

Answer 3

Speed - how fast you go
Speed = gradient - change in vertical ÷ Change in horizontal

Scalar- has a size but no direction e.g speed, temp

Vectors- have a size (magnitude) and a direction e.g force, weight

Question 4

Acceleration

Answer 4

It’s the change in velocity in a certain time
Deceleration- it’s the negative acceleration
Uniform acceleration- a constant acceleration
Acceleration = final velocity - initial velocity ÷ time

Question 5

Newton’s 1st law

Answer 5

A resultant force is needed to make something start moving, speed up or slow down

Question 6

Newton’s 2nd law

Answer 6

F = m X a

Question 7

Circular motion

Answer 7

Velocity is both speed and direction of an object
If object is travelling to the circle (at a constant speed) it’s constantly changing direction so constantly changing velocity which equals accelerating
This means that theres a resultant force acting on it.
This force acts towards the centre of the circle this is called a centripetal force

Question 8

Weight

Answer 8

Weight depends on mass and gravitational field strength
Weight is the force acting on an object due to gravity
Mass is a scaler quantity – it’s the amount of stuff in an object

Question 9

Inteitia

Answer 9

The tendency to keep moving at the same velocity

Question 10

Newton’s 3rd law

Answer 10

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

Question 11

Momentum

Answer 11

In a closed system the total momentum before and event is the same as after the event. This is called conservation of momentum
Change in momentum - force = change in momentum ÷ time (helps show Newton’s 3rd law)

Question 12

Thinking distances

Answer 12

The distance the car travels in the drivers reaction time
Affected by reaction time and speed
Ruler drop test measures reaction time

Question 13

Breaking distance

Answer 13

Distance taken to stop once brakes applied

Affected by speed, mass, condition of breaks and amounts of friction

Question 14

Stopping distances

Answer 14

Stopping distances = thinking distance + braking distance

Question 15

Energy stores

Answer 15

Kinetic, thermal, chemical, elastic potential, electrostatic, magnetic, nuclear, gravitational potential

Question 16

Transferring energy

Answer 16

Energy is never created or destroyed
Energy transferred in 4 Ways
Mechanically – force acting on an object (and doing work)
Electrically-a charge doing work
By heating – energy transferred from hotter to colder objects
By radiation – energy transferred by waves

Question 17

Efficiency

Answer 17

The less energy wasted the more efficient the device
Installation reduces the rate of energy transferred by heating
Lubrication reduces energy transferred by friction
Sankey diagrams show efficiency

Question 18

Energy resources and trends

Answer 18

Don’t renewable – fossil fuels and nuclear energy, they are reliable, creates environmental problems, will run out
Renewable – biofuels, wind, the Sun (solar) hydroelectricity, tides - won’t run out

Question 19

Newton’s second law practical

Answer 19

Set up cart so that it’s pulled through 2 light gates by a mass on a string that goes over the pulley
Starts with lowest mass
Release mass so that cart is pulled through light gates
Increase force by adding another mass and repeat previous steps
Continue adding masses measuring acceleration each time