Motion Flashcards
Velocity
Rate of change of displacement
Displacement
Distance travelled in a particular direction
To calculate the velocity
Increase in displacement ➗time taken
a = (v-u)/t
Acceleration = change in velocity ➗ time taken
Speed definition
Rate of change of distance
The gradient of a velocity time graph is equal to
The acceleration
The area under a velocity time graph is equal to
the distance travelled by the object in a particular time interval
Shallow gradient on velocity time graph
Low acceleration
Steep gradient on velocity time graph
High acceleration
Horizontal (zero gradient) on velocity time graph
No acceleration
Negative gradient on velocity time graph
Negative acceleration (deceleration)
Straight line on distance time graph
Object moving at constant speed
Scalars
Have a magnitude (size) only
Examples of scalar quantities 4
Temperature
Time
Distance
Speed
Examples of vectors 3
Force
Displacement
Velocity
In a distance time graph the gradient is equal to
The velocity
Why does the GPE decrease as the ball gets closer to the ground
Because the height above the ground is getting smaller
Why is the GPE converted into kinetic energy
Conservation of energy - energy not created or destroyed, just transferred into different types
Why does the ball accelerate towards the ground
Because it is gaining kinetic energy
Energy changes when the ball is squashed
The kinetic energy is converted into elastic potential energy
Energy changes that cause the squashed ball to move back into the air
Ball converts the elastic potential energy back into kinetic energy
Energy at the peak of the bounce
All the kinetic energy has been converted into GPE
Energy at the point where the ball is about to hit the ground
All the GPE has been converted into kinetic energy
Why is the bounce not as high as the release height
Some of the energy has been transferred to the surroundings in the form of sound & thermal energy
Once the ball has come to rest, what has happened to all the original GPE?
It has all been transferred to the surroundings
Why is force a vector
The size of a force and the direction in which it acts are both important
If the line is horizontal in a distance time graph
The object is stationary
Newtons 2nd law of motion
Resultant force is directly proportional to acceleration
Speed definition
The magnitude of velocity when the motion is in a straight line in one direction only
If the line slopes down to the right (negative gradient) on a DISTANCE-time
The distance that the object is from the starting point is now decreasing - the object is now retracing it’s path back to the start
If the line is horizontal on a distance time graph
The object is stationary
Distance definition referencing displacement
The magnitude of displacement when the motion is in a straight line in one direction only
Acceleration relation to mass observation & conclusion
1)On objects with the same mass, a smaller force will produce smaller acceleration than a larger force
2) acceleration is inversely proportional to mass
Eg doubling the mass will halve the acceleration
Acceleration relation to force observation & conclusion
1) when the same force is applied to objects with a different mass, the smaller mass will experience a greater acceleration
2) force is proportional to acceleration
Eg doubling the force acting on an object doubles it’s acceleration
Why is excessive deceleration unwanted example
If the brakes are applied too hard, the tyres will not grip the road surface & the car will skid
If you are designing a car for high acceleration, what does the equation f=ma tell you?
The car should have a low mass
The engine should supply a high acceleration force
Newton’s third law of motion
When two objects interact, the forces they exert on each other are equal and opposite
