Unit 3- Dynamics and Space

Question 1

What is a vector quantity?

Answer 1

Specified by magnitude and direction

Question 2

Vector quantities include…

Answer 2

Velocity, weight, acceleration, displacement, force

Question 3

When do you add vectors?

Answer 3

If they are in the same direction

Question 4

When do you subtract vectors?

Answer 4

If they are in the opposite direction

Question 5

What is the resultant displacement?

Answer 5

The sum of two displacements at right angles to one another

Question 6

Speed time graphs:

Constant acceleration is shown by…

Answer 6

A diagonal line going upwards

Question 7

Speed time graphs:

Constant deceleration is shown by…

Answer 7

A diagonal line going downwards

Question 8

Speed time graphs:

Constant speed is shown by…

Answer 8

A straight line

Question 9

How can the distance travelled be calculated on a speed time graph?

Answer 9

By calculating the area of each section underneath it (divide into triangles and rectangles, then find the area, then add them together)

Question 10

Name a method of measuring instantaneous speed

Answer 10

Using a speedometer in a car, or a computer connected to light gates

Question 11

How can light gates be used to measure speed?

Answer 11

Instantaneous speed= length of card/ time beam is blocked

Question 12

What is the definition of Acceleration

Answer 12

The change in velocity per unit time

Question 13

Using light gates to measure acceleration

Answer 13

You must know the
initial velocity,
the final velocity,
Time taken to pass from one light gate to another

Question 14

What is Newton’s first law?

Answer 14

An object at rest will remain at rest unless acted upon by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Question 15

What is Newton’s second law?

Answer 15

If an object is acted on by an unbalanced force it will accelerate. The amount of acceleration increases as the force increases. However if you apply the same force to a larger mass the acceleration will be less

Question 16

When does work take place?

Answer 16

When an object is moved by a force, the force transferring energy to the object

Eg/ if an archer pulls back a string on a bow and arrow the work done stretching the sting will be transferred to the arrow when it is fired

Question 17

What is the definition of gravitational field strength?

Answer 17

The force per unit mass

Question 18

What is Newton’s third law?

Answer 18

For every action force there is an equal and opposite reaction force

Question 19

Describe terminal velocity

Answer 19

When a skydiver jumps out of a plane they accelerate downwards due to the force of gravity. As their speed increases so does the force of friction (due to air resistance) eventually the weight and friction become equal.

There are now no unbalanced forces acting on them, so they continue downwards at a steady speed. They have reached their terminal velocity

Question 20

What is a projectile?

Answer 20

An object which has a forwards speed at the same time as it as falling freely through the air

Question 21

Describe the vertical motion of a projectile (in terms of a graph)

Answer 21

A diagonal line doing upwards

Question 22

Describe the horozontal motion of a projectile (in terms of a graph)

Answer 22

Straight line

Question 23

What is a satellite?

Answer 23

Like a projectile which is falling towards the earths surface at the same rate as the earths surface is curving away from the satellite. The satellite at this point is said to be in orbit

Question 24

Describe a geostationary satellite

Answer 24

They orbit the Earth once every 24 hours
They always remain in the same position above the earths surface
They are mostly used for communications and weather observation

Question 25

What are the benefits of space exploration?

Answer 25

Communication- uses satellites
Jobs- many people employed in the industry
Spin off technologies- bar codes, non stick pans
Mapping- using satellites can improve land use

Question 26

What are the risks of space exploration?

Answer 26

Danger to life- several astronauts have lost their lives in missions
Cost- the money could be spend elsewhere, the budget is high

Question 27

What are the dangers on re-entry of the atmosphere?

Answer 27

If the spacecraft hits the atmosphere at the wrong angle it can bounce back into space

The atmosphere creates friction, and so heat. The space craft may face overheating

Question 28

What is the definition of latent heat of fusion?

Answer 28

The energy added or removed from 1 kilogram of substance to change it from solid to liquid or liquid to solid

Question 29

What is the definition of a light year?

Answer 29

The distance that light will travel in one year

Question 30

How far is the sun from the earth?

Answer 30

8.5 minutes

Question 31

How far is the sun to the nearest star?

Answer 31

4.3 light years

Question 32

What is the diameter of the Milky Way?

Answer 32

120,000 light years

Question 33

What is a scalar quantity?

Answer 33

Specified by magnitude alone