Phys

What is the definition of speed?

The rate at which distance is covered.

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What is the definition of acceleration?

The rate at which velocity changes.

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What is the definition of velocity?

The speed of something in a given direction.

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What is Newtons 1st law of motion?

An object will have a constant velocity unless a resultant force acts on it.

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What is a resultant force?

The sum of more than one force.

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What is Newtons 2nd law of motion?

Resultant force = mass (kg) * acceleration (m/s squared)

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What is Newtons 3rd law of motion?

If object A exerts a force on object B, then object A exerts an equal force on object direction.

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Describe how forces affect someone jumping out of a plane.

First, the only force acting is weight so they accelerate downward. As speed increases, air resistance increases. Eventually weight & air resistance balance, so no resultant force & constant speed reached.

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Describe how forces affect someone jumping out of a plane.cont.

When the parachute opens, air resistance gets bigger than weight so the person starts to decelerate. Finally weight and air resistance balance again and a terminal but lower speed is reached.

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What is stopping distance?

The sum of the breaking and thinking distance.

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What is friction?

One of the forces the road exerts on the tyres as the car is stopping.

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What is thinking distance?

The distance the car travels before the breaks are applied.

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What is breaking distance?

The distance the car travels whilst the breaks are applied.

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What factors affect thinking distance distance?

Bad weather, like fog. Tiredness. Alcohol and drugs. Distractions.

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What factors affect breaking distance?

Higher speed. Poor road conditions (icy, wet). Car conditions (bald tyres, poor brakes).

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When is 'work done' on an elastic object?

When it changes shape and stores elastic potential energy.

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What is the extension of an elastic band directly proportional to?

The force applied to it.

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When is work done on an object?

When an object is moved by force.

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Why is energy stored in an object?

Because of its position in the arts gravitational field.

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What is conservation of momentum?

When no external forces are acting on the objects involved, the total momentum stays the same in explosions and collisions.

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What speed is shown by this graph?

Steady speed.

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What speed is shown by this graph?

Fast constant speed.

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What speed is shown by this graph?

Slow constant speed.

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What speed is shown by this graph?

Not moving.

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What speed is shown by this graph?

Constant backwards speed.

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What speed is shown by this graph?

Quick acceleration.

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What is the definition of power?

The rate at which energy is transferred.

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What are the units of power, energy, ant time?

Power = watts. Energy = joules. Time = seconds.

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What is the equation for wasted power?

Total power in - useful power out.

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List safety features of cars.

Seat belts, air bags, crumple zones, NCAP safety reviews, seat belt pretensioners and preloaders.

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What happens as a moving car stops?

Moving cars have kinetic energy. As energy cannot be created or destroyed, when a car brakes its kinetic energy changes into heat energy. The brakes heat up and then transfer the energy to the surroundings.

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What is the purpose of car safety features?

To increase impacts time to therefore decrease the impact force and save someones life.

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What happens if you add electrons to an uncharged atom?

It becomes negatively charged.

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What happens if you remove electrons to an uncharged atom?

It becomes positively charged.

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