Forces

What are forces and what do they do?

Forces are pushes or pulls. They change the speed, shape or direction of objects.

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What are forces measured in?

Newtons

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List four contact forces.

Upthrust, Friction, push & pull, air resistance.

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List four non-contact forces.

Gravity, Weight, magnesium, electrostatic.

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What are vector quantities?

Vector quantities are forces that have a magnitude (size) and direction.

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What are scalar quantities?

Scalar quantities are forces with just a magnitude (size).

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List four vector quantities.

Acceleration, displacement, force, electric current, velocity, moment, momentum, filed strength.

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List four scalar quantities.

Time, speed, mass, temperature, energy, volume, charge, pressure, frequency, distance.

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List the properties of weight.

It is lower on the moon than on the Earth, it is caused by the pull of gravity, measured in newtons, is a force and is measured by a spring balance.

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List the properties of mass.

It is measured by a balance, not a force, same anywhere in the universe, measured in kilograms, amount of matter.

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What is the relationship between mass and weight?

100g is equal to 1N. This shows that weight is directly proportional to mass. The weight is always 10 times the mass.

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What is the equation that links gravity, mass and weight and what are they measured in?

weight(N) = mass(kg) * gravitational field strength(N/kg or m/s2)

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Find the mass of a rock with the weight of 155N on Earth.

W=m*g, m=W/g, m=155/10, m=15.5kg

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List the properties of speed.

It is how fast an object is moving, it is a scalar quantity and is measured in m/s.

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What is the equation that links speed, time and distance and what are they measure in?

Speed(m/s) = distance(m)/time(s)

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What is velocity?

Velocity is how fast an object is moving in a given direction. It is a vector quantity.

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What is the equation that links velocity, time and displacement and what are they measured in?

Velocity(m/s) = displacement(m)/time(s)

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What is acceleration?

Acceleration is the rate at which objects increase their velocity.

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What is the equation that links acceleration, velocity and time and what are they measured in?

Acceleration(m/s2) = change in velocity(m/s)/time(s)

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How do you find the distance travelled on a velocity/time graph?

The area under the line of the graph.

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What is the equation that links force, acceleration and mass and what are they measured in?

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

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What do resultant forces cause?

They cause acceleration or deceleration.

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What is the equation that links force, velocity and time and what are they measured in?

Force(N) = (mass(kg) * change in velocity(m/s))/time(s)

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What is the equation that links braking distance, stopping distance and thinking distance?

Stopping distance = braking distance + thinking distance

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What is thinking distance?

Thinking distance is the distance travelled whilst realising you need to stop accelerating/brake.

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What is braking distance?

Braking distance is the distance travelled whilst you brake.

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Give two items that affect thinking distance.

Alcohol, Drugs or medication, Tiredness or use of mobile phone.

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Give two items that affect braking distance.

Tyre wear, faulty brakes, mass of the car, weather.

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Give an item that affects both braking and thinking distance.

Speed of the car.

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