P2 Forces

Flashcards by dfreeman, updated more than 1 year ago
Created by dfreeman over 5 years ago


GCSE Physics (AQA GCSE) Flashcards on P2 Forces, created by dfreeman on 05/14/2014.

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Question Answer
Whenever two objects interact, the forces they exert on each other are... Whenever two objects interact, the forces they exert on each other are equal and opposite.
What is meant by resultant force? A number of forces acting at a point may be replaced by a single force that has the same effect on the motion as the original forces all acting together. This single force is called the resultant force.
What do resultant forces cause? A resultant force acting on an object may cause a change in its state of rest or motion.
What is the effect of resultant forces on stationary objects If the resultant force acting on a stationary object is: ■ zero, the object will remain stationary ■ not zero, the object will accelerate in the direction of the resultant force.
How is force, mass and acceleration linked? The acceleration of an object is determined by the resultant force acting on the object and the mass of the object. a=F/m or F=m×a
What does the gradient of a distance–time graph represent? The gradient of a distance–time graph represents speed.
How can acceleration be calculated? The acceleration of an object is given by the equation: a=(v-u)/t
What does the gradient of a velocity–time graph represent? The gradient of a velocity–time graph represents acceleration.
How can distance be calculated from a velocity-time graph? Area under the graph
Describe the forces acting when a vehicle travels at a steady speed When a vehicle travels at a steady speed the resistive forces balance the driving force.
What is a car's stopping distance? What parts make it up? The stopping distance of a vehicle is the sum of the distance the vehicle travels during the driver’s reaction time (thinking distance) and the distance it travels under the braking force (braking distance).
What factors can affect a driver's reaction time? A driver’s reaction time can be affected by tiredness, drugs and alcohol.
How do car brakes slow a car? When the brakes of a vehicle are applied, work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increase.
What factors can affect a car's braking distance? A vehicle’s braking distance can be affected by adverse road and weather conditions and poor condition of the vehicle.
How does drag change with speed? The faster an object moves through a fluid the greater the frictional force that acts on it.
Describe the motion of a falling object in a fluid An object falling through a fluid will initially accelerate due to the force of gravity. Eventually the resultant force will be zero and the object will move at its terminal velocity (steady speed).
How is weight calculated? Calculate the weight of an object using the force exerted on it by a gravitational force: W=m×g
What can affect the shape of an object? A force acting on an object may cause a change in shape of the object.
What can a force do to an elastic object? A force applied to an elastic object such as a spring will result in the object stretching and storing elastic potential energy.
What is stored in a stretched spring? For an object that is able to recover its original shape, elastic potential energy is stored in the object when work is done on the object to change its shape.
How are force and extension linked in an elastic object? The extension of an elastic object is directly proportional to the force applied, provided that the limit of proportionality is not exceeded: F=k×e
What causes work to be done? When a force causes an object to move through a distance work is done.
Calculate work done Work done, force and distance are related by the equation: W=F×d
What is work done the same as? Energy is transferred when work is done.
What is power? How is it calculated? Power is the work done or energy transferred in a given time: P=E/t
What is gravitational potential energy? How is it calculated? Gravitational potential energy is the energy that an object has by virtue of its position in a gravitational field. Ep=m×g×h
What is kinetic energy? How is it calculated? The kinetic energy of an object depends on its mass and its speed. Ek=1/2×m×v^2
How is momentum calculated? Momentum is a property of moving objects. p=m×v
What is conservation of momentum? In a closed system the total momentum before an event is equal to the total momentum after the event. This is called conservation of momentum.
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