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Description
Flashcards by Monika Rhys-Jones, updated more than 1 year ago
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Created by Monika Rhys-Jones
over 9 years ago
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| Question | Answer |
| How are forces represented? | with an arrow from where the force originates |
| What is a resultant force? | -a single force which replaces all the other forces -same effect as all the forces together |
| What will happen if the resultant force acting on a stationary object is 0? | the object will stay stationary |
| What will happen if the resultant force acting on a stationary object is not 0? | the object will accelerate in the direction of the resultant force |
| What will happen if the resultant force on a moving object is 0? | the object will move at the same speed in the same direction |
| What will happen if the resultant force on a moving object is not 0? | it will speed up, slow down or change direction |
| What is the unit for force? | Newtons (N) |
| How are force, mass and acceleration linked? | force = mass x acceleration |
| What uni is mass in? | kg |
| What unit is acceleration in? | m/s squared |
| What does the gradient of a distance time graph represent? | speed (velocity) |
| What are the units of speed? | m/s or km/hr |
| What does a horizontal line on a distance time graph mean? | object is stationary |
| How do you calculate speed from a distance time graph? | distance/time |
| What does the gradient of a velocity time graph represent? | acceleration |
| What does a horizontal line on a velocity time graph represent? | the object is moving at a constant speed |
| How do you calculate acceleration from a velocity time graph? | final velocity - initial velocity divided by time |
| How do you calculate distance from a velocity time graph? | area underneath line in metres |
| What happens to the forces when a vehicle travels at a constant speed? | the resistive forces balance the driving forces |
| Which force are most of the resistive forces acting on a vehicle? | air resistance or drag |
| How is the braking force affected by speed? | the bigger the speed the greater the braking force needed to stop it in a certain distance |
| What is stopping distance? | distance vehicle travels in reaction time + distance travelled under braking force |
| What can a driver's reaction time be affected by? | tiredness, drugs and alcohol |
| What happens to the temperature of the brakes when you apple them and why? | -increases -work done by friction between the brakes and wheel reduces the kinetic energy of the wheel so the temp of the brakes increases |
| What can braking distance be affected by? | poor weather (icy or wet) and condition of vehicle (brakes and tyres) |
| When an object moves (through a fluid), what happens to the frictional force? | it increases |
| Why does a falling object initially accelerate? | due to gravity |
| What will eventually happen to the resultant force of a falling object? | it will be zero |
| What is terminal velocity? | the speed an object reaches when its resultant force is 0 |
| How do you calculate the weight of an object? | mass x gravity |
| What will happen to a spring when a force is applied to it? | it will change shape and stretch |
| What type of energy is stored in a spring when it is stretched? | elastic potential energy |
| What is the limit of proportionality? | the point at which the force applied and extension is no longer proportional |
| What are the units for spring constant? | N/m |
| What is work done? | when a force causes an object to move through a distance |
| What is the unit for work done? | Joules (J) |
| What is transferred when work is done on an object? | energy |
| Will the amount of work done to move an object be smaller or greater than to move the same object the same distance across grass? | it will be smaller because there are less frictional forces to counteract |
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