Unit 2 - Forces + Motion

Question 1

What is the unit for weight

Answer 1

Newtons (N)

Weight is a force

Question 2

Unit for distance

Answer 2

Metre (m)

Question 3

Unit for velocity

Answer 3

Metre/second (m/s)

Question 4

Unit for acceleration

Answer 4

Metres per second per second (m/s²)

Question 5

Unit of measure for any force

Answer 5

Newton (N)

Question 6

Is speed scalar or vector ?

Answer 6

Speed is a scalar quality (does not have a direction)

Question 7

Is velocity scalar or vector?

Answer 7

Velocity is a vector quantity as it has a direction.
ie. Travelling at 4m/s north = 4m/s velocity
Travelling at 4m/s south = -4m/s velocity

Question 8

Is force vector or scalar ?

Answer 8

All force has a direction and therefore force is a vector quantity

Question 9

Average speed (m/s) =

Answer 9

Distance moved (m) / time taken (s)

Question 10

Acceleration (m/s²) =

Answer 10

Change in velocity (m/s) / time taken (s)

*deceleration is negative (slowing down)

Question 11

In a distance/time graph, the gradient =

Answer 11

The speed.

Speed = distance/time

Question 12

In a distance/time graph, a horizontal line means …

Answer 12

The object is still

Question 13

In a velocity/time graph, the gradient =

Answer 13

Acceleration

Acceleration = v-u / time 
v = start velocity 
u = new velocity

Question 14

In a velocity/time graph, a horizontal line means ..

Answer 14

That the object is travelling at constant velocity

Question 15

The area underneath a velocity/time graph =

Answer 15

The distance travelled

Question 16

What is relationship between force, mass, and acceleration

Answer 16

Force (N) = mass (kg) X acceleration (m/s²)

Question 17

Relationship between weight, mass, and gravity (g)

Answer 17

Weight (N) = mass (kg) X gravity (g)

Question 18

When does an object reach terminal velocity ?

Answer 18

When the forces acting against an object (drag or resistance) equal the gravitational pull of the object

Question 19

What factors affect a vehicles stopping distance ?

Answer 19

Speed, mass of car, road conditions, reaction time

Question 20

What is the thinking distance ?

Answer 20

The distance travelled between the driver reacting and when they actually hit the brakes

Question 21

What factors affect thinking distance

Answer 21

SPEED, mental state of driver (drunk, tired, distracted), visibility

Question 22

Momentum =

Answer 22

Momentum (kg m/s) = mass (kg) X velocity (m/s)

Question 23

Unit of measure for momentum

Answer 23

Kilogram metre/second (kg m/s)

Question 24

Newtons 1st law

Answer 24

Objects will stay stationary, or continue to move with constant speed, unless an unbalanced force acts upon then.

Question 25

Newtons 2nd law

Answer 25

The acceleration produced by a force when it acts on a body is proportional to the force and takes place in the same direction as the force

Question 26

Newtons 3rd law **

Answer 26

To every force, there is an equal and opposite reaction force

Question 27

Law of conservation of momentum

Answer 27

So long as no external forces are acting on the objects involved, the total momentum before a collision is the same as the total momentum after the collision

Question 28

Relationship between force, change in momentum, and time

Answer 28

Force (N) = change in momentum (kg m/s) / time taken (s)

Question 29

What is the unit for mass

Answer 29

Kilogram (kg)

Question 30

What is friction

Answer 30

A force that opposes motion

Question 31

What is instantaneous speed

Answer 31

Speed in the exact moment

Question 32

What effects can a force have on a body?

Answer 32

Changes in speed, shape, or direction

Question 33

What are the forces acting on a falling object

Answer 33

Downward: weight (gravitational) | Upward : air resistance (drag)

Question 34

How to use the conservation of momentum to calculate the mass, velocity or momentum of objects

Answer 34

Momentum (kg m/s) = mass (kg) x velocity(m/s) Velocity= momentum / mass Mass= momentum / velocity If a bullet with a mass of 0.2g is shot from a gun at 100 m/s to work out its momentum we do 0.2g x 100 m/s = 20 g m/s.

Question 35

How do seat belts reduce risk (momentum)

Answer 35

*force = change in momentum / time* The stretchy material that seat belts are made of make the time taken to come to a complete stop take longer. By increasing the time taken to stop, it decrease the amount of force exerted on the passenger (*)

Question 36

Unit for moment

Answer 36

Newtons per metre (N/M)

Question 37

Moment =

Answer 37

Moment = force (N) X perpendicular distance from pivot (M)

Question 38

Where in an object does weight act?

Answer 38

The weight of a body acts through its centre of gravity

Question 39

What is Hookes law

Answer 39

Hooke's law states that the extension is proportional to the applied force (load), provided that the elastic limit is not exceeded

Question 40

What is elastic behaviour

Answer 40

Elastic behaviour is the ability of a material to recover its original shape after the forces causing deformation (load) has been removed

Question 41

What is the different between the orbits of comets, moons, and planets

Answer 41

The orbit of moons and planets are described as circular (even though they are slightly elliptical). Planets orbit starts Moons orbit planets Comets orbit stars, however their orbit is EXTREMELY elliptical

Question 42

Orbital speed (Km per day) =

Answer 42

(2π X orbital radius (km)) / time period (days)

Question 43

What is the universe

Answer 43

The universe is a large collection of billions of galaxies

Question 44

What is a galaxy

Answer 44

A galaxy is a large collection of billions of stars

Question 45

Where is our solar system

Answer 45

In the Milky Way Galaxy

Question 46

What is g on earth

Answer 46

10N/Kg

Question 47

What is g on the moon

Answer 47

1.6 N/Kg

Question 48

What is gravitational field strength

Answer 48

Gravitational field strength is what causes objects to have weight. It is different on all planets/moons/comets. The more mass an object has, the more gravitational field strength it has

Question 49

What is the principle of moments

Answer 49

When an object is in equilibrium (balanced), the sum of the clockwise moment about a point must be equal to the sum of the anti-clockwise moment about the same point

Question 50

Experiment to investigate how extension varies with applied forces for helical Spring, metal wires, and rubber bands

Answer 50

Attach a spring to a newton meter and measure its length Add a 50g weight and measure again continue to add another weight and take another measurement Do this up to 400g by plotting a graph from the results from this you can see the extension increases with force; as each time a weight is added the spring gets longer.

Question 51

How to the upward forces on a light beam, supported at its ends, vary depending on the position of heavy object placed on a beam

Answer 51

This means you need to understand that if you have say a plank of wood being held in balance by springs pushing up at the ends and you put a weight on the beam, the springs would have to exert more force as they need to equal the downward force.