Motion and Forces

What is a vector quantity?

a quantity that has both magnitude and direction

What is a scalar quantity?

A quantity that has only magnitude

Examples of vector quantities

force, velocity, displacement, acceleration, momentum

Examples of scalar quantities

Speed, distance, mass, energy, temperature, time.

What is velocity(Scalar or Vector and why)

Vector because it's Speed in a given DIRECTION

What is speed and why

Scalar because it is just how fast something is moving.

What is distance and why

Scalar because it's just how far an object has moved

What is displacement and why

It measures the distance and direction in a straight line from a starting point.

Formula for distance, speed and time

Distance traveled (m) = speed (m/s) x time (s)

Average walking speed

1.5 m/s

Average running speed

3 m/s

average cycling speed

5.5 m/s

Average car speed

25 m/s

What is acceleration

The change in velocity in a certain amount of time

Equation for acceleration

change in velocity/time

Equation for constant acceleration

final velocity^2- initial velocity^2 = 2 x acceleration x distance

On a distance time graph what does the gradient mean

The speed of the object

On a distance time graph what does a flat line mean

stopped

On a distance time graph what does a steeper line mean

Going faster

On a distance time graph what does curves represent

Acceleration

How do you work out speed from a distance time graph

Distance/time.

What does a flat line mean on a velocity time graph

constant speed

What does an uphill line mean in a velocity time graph

Acceleration

How do you work out distance traveled on a velocity time graph

Area under the graph meaning u may need to do triangles.

What is weight

the force of gravity on an object

What is mass

the amount of matter in an object

When drawing forces do arrows need to be bigger if the force is bigger

Yes

What is Newton's first law?

An object will remain at rest or travelling at a constant velocity unless it is acted on by a resultant force.

What is a resultant force?

The overall force on a point or object

What is a force?

A push or a pole on an object caused by it interacting with something

Equation for resultant force

Resultant force = mass x acceleration

What is weight measured in?

Newtons

What is mass measured in?

kg

How do you measure weight? With what device?

A newton meter (collaborated spring)

Equation for weight

Weight = mass x gravitational field strength

What is the gravitation field strength on earth?

10N/kg

When moving in a circular motion what is constantly changing

Velocity

What does it mean if the velocity is constantly changing if moving in a circular motion

It's accelerating

If something is constantly changing direction when moving in a circle around a point, where is the force acting and what is this force called?

The force acts towards the centre of the circle and it's called centripetal force.

What are some examples of centripetal force?

Washing machine, carousel or turning round a roundabout

What is Newton's second law?

The acceleration of an object is proportional to the resultant force acting on the object, and inversely proportional to its mass.

What does Newton's second law mean with relation to mass and acceleration?

The lower the mass the faster an object will accelerate/decelerate.

What is acceleration?

The rate at which velocity changes

What is inertial mass?

A measure of how difficult it is to change the velocity of an object

What is Newton's third law?

When two objects interact, the force they exert on each other is equal and opposite.

So if I'm pushing a trolley why do I not move away like the trolley?

I have a higher mass fatty.

What is an equilibrium?

a state in which opposing forces or influences are balanced.

What is an action reaction pair

The reaction to an action. For example when you push on a box the box pushes back at you. Your push is action, box's is reaction

What is the difference between action reaction pairs and balanced forces?

Balanced forces cancel out because they act on the same object. Action reaction don't!

How do you calculate momentum

mass x velocity

Unit of momentum

kg m/s

What happens to momentum after a collision

It is transferred and not lost

Equation to work out force needed for a change in momentum

Force=acceleration(change in momentum)/time

What is a stopping distance and what is it made up of

The distance covered between first spotting a hazard and coming to a complete stop. Made up of thinking distance and braking distance.

Equation for stopping distance

Stopping distance = thinking distance + braking distance

Factors which can affect thinking distance

Reaction time (tiredness, alcohol, drugs, distraction). Speed (faster your going the further you'll travel in your reaction time).

What factors affect braking distance

Speed, mass (won't stop as quick), condition of brakes, friction between tires and road.

What is the average reaction time for a human

0.2 seconds

How can reaction times be measured?

Ruler drop test.

What dangers are caused by large decelerations and why?

Loose control of brakes and crash and it's because it requires a lot of force.

What does work done mean?

How much energy is transferred

Work done equation

force x distance