Physics 2a Flashcards
What is the difference between speed and velocity?
Speed is just how fast you’re going but Velocity also has the direction specified eg. 30mph north.
How do you calculate speed?
distance/time.
What does the Gradient of a distance-time graph tell you and how do you calculate it?
1) It tells you the speed of your object.
2) Speed= vertical/ horizontal distance/ time
What is acceleration?
It is how quickly velocity is changing.
the change in velocity can be in speed or direction.
How do you calculate acceleration and what is it’s unit?
1) Change in velocity/ time taken. (change in velocity= final velocity- initial velocity).
2) m/s squared
What is a resultant force?
The overall force on a point or object.
What unit are forces measured in?
Newtons
How do you calculate a resultant force/
You do a force from one direction- the force from the other if it equals zero then the object has no resultant force.
What does it mean for an object if it does have a resultant force?
It will accelerate or decelerate.
What happens if there is no resultant force on a moving object?
It will continue at the same velocity, not become stationary.
What are the five different forms that acceleration can result in?
1) starting
2) Stopping
3) Speeding up
4) Slowing down
5) Changing direction
how do you calculate force?
mass (kg) x Acceleration (metres per second squared)
what forces will two objects exert on each other when they interact?
equal and opposite forces.
Where do you get friction and what does it do?
1) You get friction between two surfaces in contact, or when a object passes through a fluid.
2) It acts in the opposite direction to movement and slows the object down.
What is terminal velocity?
When an object stops accelerating and reaches it’s maximum speed and continues at a steady speed.
What does air resistance do?
It causes things to fall at different speeds depending on the surface area.
What would opening a parachute do to a skydiver’s terminal velocity?
It would bring the number down by a lot.
How do you calculate stopping distance?
The sum of the thinking distance and the braking distance.
What is reaction time and what is the distance covered during this time called?
1) The time between the driver spotting a hazard and taking action.
2) Thinking distance.
What are the two main factors that affect your thinking distance?
1) How fast you’re going.
2) How dopey you are (could be affected by tiredness, drugs or alcohol).
What is braking distance?
The distance the car travels under braking force.
What are the four main factors that affect braking distance?
1) How fast you’re going.
2) How good your brakes are.
3) How good your tyres are.
4) How good the grip is.
How do you calculate work done?
Force(N) x distance(m) = work done(J)
What is work done?
When a force moves an object through a distance.
How do you calculate gravitational potential energy?
mass x g(10N/kg) x height.
How do you calculate kinetic energy?
1/2 x mass x speed squared.
What do these symbols mean when working out the kinetic energy transferred by a car?
1/2 x m x v squared = F x d
m= mass of car and passengers(in kg) v= speed of car(in m/s) F= maximum braking force (in N). d= braking distance (in m)
What do falling objects convert potential energy to?
Kinetic energy.
What two other types of energy is kinetic energy often transferred to?
heat and sound.
what happens to elastic potential energy when force is removed from it?
It is converted into kinetic energy.
What is a positive static charge caused by?
Electrons moving else where.
What is the build up of static caused by?
Friction
What happens when two insulating materials are rubbed together?
negatively charged
