Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
45 Cards in this Set
- Front
- Back
|
Define acceleration. |
The speed at which the velocity of an object is changing. This change in velocity can be a change in speed or a change in direction or both. |
|
|
Give the formula for acceleration. |
Change in velocity Acceleration = -------------------------- Time |
|
|
What is the unit that acceleration is measured in? |
m/s² (metres per second squared) |
|
|
In a velocity time graph, what does the gradient of the line show? |
Acceleration |
|
|
In a velocity time graph, what do: b) Uphill sections c) Downhill sections d) A curve represent? |
a) Steady speed b) Acceleration c) Deceleration d) Changing acceleration |
|
|
In a velocity-time graph, what does the area under the graph (or under sections of the graph) equal? |
The distance travelled in that time interval. |
|
|
Complete this sentence: The steeper the graph... |
...the greater the acceleration. |
|
|
How can you use a velocity-time graph to calculate the acceleration of an object? |
vertical change -------------------------- = gradient = acceleration horizontal change |
|
|
What is gravity? |
The force of attraction between all masses. |
|
|
What are gravity's two important effects? |
1) On the surface of a planet, it makes all things accelerate towards the ground (all with the same acceleration). 2) It gives everything a weight. |
|
|
What is mass? |
The amount of matter an object contains, measured in kilograms. |
|
|
What is weight? |
It is caused by the pull of the gravitational force and is measured in Newtons. The weight of an object is just the force of gravity pulling it towards the centre of the Earth. |
|
|
True or false: An object with a mass of 5kg on Earth will have a mass of 5kg on the moon. |
True. The mass on the object does not change - but the weight does. The object will weigh less on the moon because the gravitational force pulling on it is less. |
|
|
What instrument is used to measure weight? |
A Newton meter or a spring balance. |
|
|
What instrument is used to measure mass? |
A mass balance. |
|
|
State the formula that relates mass, weight and gravity. |
weight = mass x gravitational field strength w = m x g |
|
|
What is acceleration of an object determined by? |
The resultant force acting on the object and the mass of the object. |
|
|
What are speed and velocity measured in? |
m/s (metres per seconds) |
|
|
What is the difference between speed and velocity? |
Speed is just how fast you're going - velocity is speed PLUS a direction. |
|
|
What is the formula that links speed, distance and time? |
Distance ------------- = Speed Time |
|
|
What does the gradient of a distance-time graph tell you? |
How fast the object is travelling. This is because the gradient is the change in the distance (vertical axis) divided by the change in time (horizontal axis). |
|
|
In a time-velocity graph, what do:
a) Flat sections b) Straight (up/down) sections c) Downhill sections d) A steepening curve e) A levelling off curve represent? |
a) The object is stationary b) It's travelling at a steady speed c) The object is going back towards its starting point. d) Acceleration - the object is speeding up e) Deceleration - the object is slowing down |
|
|
What is a resultant force? |
The overall force on a point or object. |
|
|
What does the overall effect of the forces acting on an object determine? |
The motion of the object; whether it was accelerate, decelerate or stay at a steady speed. |
|
|
If forces all act along the same line (they're all parallel and act in the same of the opposite direction), how can the resultant force be found? |
By adding or subtracting them. |
|
|
If there is a resultant force acting on an object, what will happen? |
The object will change its state of rest or motion - there will be a change in the object's velocity. |
|
|
What was the name of the man who presented the Laws of Motion? |
Isaac Newton. |
|
|
Describe Newton's first law - balanced forces. |
The first law states that if a body is at rest and the forces acting on it are balanced (there is no resultant force) then the body will remain at rest. However if the body is moving and the forces acting are balanced then the body will keep moving at constant speed in a straight line. |
|
|
Describe Newton's second law - unbalanced forces. |
Newton's second law is concerned with unbalanced forces. Unbalanced forces (a resultant force) produce acceleration. The bigger the unbalanced force the bigger the acceleration. This law is usually written as an equation: F = ma. |
|
|
Describe Newton's third law - equal and opposite forces. |
It states that, "If A exerts a force on B, then B exerts an equal but opposite force on A". |
|
|
What five different forms does acceleration take? |
Starting, stopping, speeding up, slowing down, changing direction. |
|
|
What is the formula that relates force, mass and acceleration? |
Force = mass x acceleration F = ma OR acceleration = force / mass a = F/m |
|
|
Complete the sentence: When two objects interact... |
...the forces they exert of each other are equal and opposite. |
|
|
If body A weighs 5kg and exerts a force on body B, which weighs 10kg, which will travel further? Why? |
Body A because its mass is smaller - acceleration is inversely proportionate to the mass of an object, so the greater the mass, the smaller the object's acceleration. |
|
|
Finish this sentence: |
...the bigger braking force it'll need. |
|
|
Finish this sentence: |
...the greater your stopping distance. However, in real life, if your maximum braking force isn't enough, you'll go further before you stop. |
|
|
What is the total stopping distance of a vehicle? |
The distance covered in the time between the driver first spotting a hazard and the vehicle coming to a complete stop. |
|
|
What is the stopping distance the sum of? |
Stopping distance is the sum of the thinking distance and the braking distance. |
|
|
What two main factors is thinking distance affected by? |
1) How fast you're going - whatever your reaction time, the faster you're going, the further you'll go. 2) Reaction time - affected by tiredness, drugs, alcohol, etc. |
|
|
What are major factors in accidents? Why does this make you more likely to crash? |
Bad visibility and distractions can also be a major factor in accidents - lashing rain, bright lights, an argument, might mean that a driver doesn't notice a hazard until they're quite close to it. It doesn't affect your thinking distance, but you start thinking about stopping nearer to the hazard, so you're more likely to crash. |
|
|
What are the four main factors in braking distance? |
1) How fast you're going 2) How good the brakes are 3) How good the tyres are 4) How good the grip is |
|
|
Describe how tyres affect braking distance. |
Tyres should have a minimum tread depth of 1.6mm in order to be able to rid of the water in wet conditions. Leaves, diesel spills and muck on the road can greatly increase the braking distance, and cause the car to skid too. |
|
|
Describe how brakes affect braking distance. |
All brakes must be checked and maintained regularly. Worn or faulty brakes will let you down catastrophically just when you need them the most. |
|
|
What does the strength of the grip on the road depend on? |
1) Road surface 2) Weather conditions 3) Tyres |
|
|
Why do you travel further after braking when roads are icy? |
The grip is weaker, which means there is less friction between the tyres and the road, meaning that the vehicle travels further before the forces acting on it are great enough to stop the vehicle. |
