ODU

Question 1

What does the gradient of a st graph give?

Answer 1

The velocity of the object

Question 2

What does the gradient of a vt graph give?

Answer 2

The acceleration of the object

Question 3

Resolving vector formulas

(Velocity / force)

Answer 3

F(h) = Fcosθ
F(v) = Fsinθ

Question 4

Newtons 1st Law

Answer 4

An object will remain at rest or continue to move in a straight line at a constant speed unless acted upon by an unbalanced force

Question 5

Newtons 2nd Law

Answer 5

An object will accelerate if acted upon by an unbalanced force
F=ma

Question 6

Newtons 3rd Law

Answer 6

Every action force has an equal and opposite reaction force
If A exerts a force on B then B will exert an equal and opposite force on A

Question 7

Why does acceleration of a rocket increase when it rises (thrust does not change)

Answer 7

Unbalanced force due to
-burnt fuel decreasing mass
-thinner air reducing friction
-g decreases so weight is less

Question 8

Steps to calculate tension

Answer 8

•Acceleration of system (unbalanced force/total mass)
•Tension (second mass x a)

Question 9

Component of weight

Answer 9

Down slope: F=mgsin θ
Perp to slope: F=mgcos θ

Question 10

Law of conservation of energy

Answer 10

Energy cannot be created or destroyed, only converted from one type to another

Question 11

Definition of power

Answer 11

The rate at which energy is converted

Question 12

Conservation of momentum law

Answer 12

The total momentum before a collision is equal to the total momentum after a collision in the absence of external forces

Question 13

When is a collision inelastic

Answer 13

A collision is inelastic when the kinetic energy before the collision is greater then the kinetic energy after the collision

Question 14

Area under a force time graph gives…

Answer 14

Impulse

Question 15

Explain how air bags/crumple zones/bike helmets work

Answer 15

•Ft=mv-mu
•need to decrease force
•can’t change the change in momentum
•have to increase t
•greater time = smaller force
•less injury/damage

Question 16

Einstein’s postulates (for relativity)

Answer 16

The laws of physics are the same for all observers
The speed of light never changes

Question 17

What happens to time?
What is t’?

Answer 17

Time dilates (gets longer)
Observed time

Question 18

What happens to length?
What is l’?

Answer 18

Length contracts (gets shorter)
Observer length

Question 19

Define Doppler shift

Answer 19

The Doppler effect is the change in observer frequency of a wave when a source of the observer is moving.

Question 20

What do - and + mean in Doppler shift formula

Answer 20

• towards
  + away

Question 21

What does hubbles law state

Answer 21

The further away a galaxy is, the faster it is moving away

Question 22

What is dark energy

Answer 22

A force that opposes gravity and causes the expansion of the universe

Question 23

Evidence of Big Bang

Answer 23

•Expanding universe
•Cosmic Microwave Background Radiation
•Abundance of light elements

Question 24

What happens to
•the peak intensity wavelength &
•the energy/intensity
of an object when the temperature increases?

Answer 24

•peak intensity wavelength decreases
•intensity/energy increases

Question 25

What is acceleration of an object in free fall

Answer 25

9.8ms

Question 26

Explain how a student would determine whether a collision is elastic or inelastic

Answer 26

Calculate the total kinetic energy before and (total kinetic energy) after.

If Ek before is equal to Ek after the collision, is elastic.