Unit 2A - Motion, Energy And Electricity Flashcards
On a distance time graph what does the gradient represent?
Speed
What’s the difference between speed and velocity?
Speed - how’re fast you are going with no regard to direction
Velocity - how fast you are going with a specified direction
On a distance-time graph what are acceleration and deceleration shown by?
Curves
If you are stationary what is this shown as on a distance-time graph?
Flat line
How do you calculate speed from distance time graphs?
Speed = gradient = y/x
What is acceleration?
Acceleration is how quickly velocity is changing
What is the formula for acceleration?
Acceleration = Change in velocity / Time
A car accelerates from 2m/s to 6m/s in 5.6s. What it’s acceleration?
0.71m/s^2
In a velocity-time graph what does the gradient represent?
Acceleration
What do flat sections represent on velocity-time graphs?
Steady speed
What is acceleration shown by in velocity-time graphs?
Straight uphill line
What does the area under a velocity-time graph represent?
Distance travelled
What does a curve means in a velocity-time graph?
Changing acceleration
What is gravitational force?
Gravitational force is the force of attraction between all masses
Are weight and mass the same?
No
What is the difference between mass and weight?
Mass is the amount of “stuff” in an object where as weight is caused by the pull of gravitational force.
Between the earth and the moon will the mass and weight be the same?
The mass will stay the same however the weight will change because there is less or more gravitational force
What is the formula for weight?
Weight = mass x gravitational field strength
What is the gravitational field strength one earth?
10N/kg
What is the resultant force?
Resultant force is the overall force on a point or object
If there is a resultant force acting on an object what will it change?
A resultant force will change the velocity
On a car there is a driving force of 1000N and air resistance of 600N , what is the resultant force?
400N to the left, causing an acceleration
If there is is no resultant force on a stationary object what will happen?
The object will remain stationary
If there is no resultant force in a moving object what will happen?
The moving object will carry on moving at a constant velocity
Is there a non-zero resultant force on a object what happens?
The object will accelerate in the direction of the force
What is the formula for resultant force?
F = MA
F being the resultant force
Is a reaction force equal or different?
Equal
What is the definition of a reaction force?
When two objects interact, the force they exert on each other are equal and opposite, this is called a reaction force
If you push something does it push you back just as hard or not as hard?
Just as hard
What is the two other name for friction and where do they apply?
Fluids (air or liquids) - drag and resistance
What does friction do?
Slow things down
What is terminal velocity?
Terminal velocity is the maximum speed an object can reach
Why does an object reach terminal velocity?
When an object first sets off falling the force of gravity is a lot higher than the force of friction, this causes the object to accelerate. As the speed increases the causes the friction to build up, and gradually reduce the acceleration. Eventually the friction force and the accelerating force is equal and the object won’t accelerate any more, it has reached its maximum velocity
Terminal velocity of falling objects is due to?
Their shape and area
Would you want a higher or lower terminal velocity if you were a skydiver? And how would you do this?
You would need a lower terminal velocity to make it safer you can do this by using a parachute which increases the area meaning there is more drag slowing you down
What is stopping distance the sum of?
Stopping distance is the sum of the thinking distance and breaking distance?
What is the distance the vehicle travels during the drivers reaction time called?
Thinking distance
What is breaking distance?
The distance the car travels under the breaking force
What are the two main factors that affect thinking distance?
How fast you’re going, how dopey you are
What are the four main factors affecting braking distance?
How fast you’re going, how good your brakes are, how good your tyres are, how good your grip is
What are the other two factors that are a major factor in accidents?
Bad visibility - rain
Distractions - radio
What is the definition of work done?
When a force moves an object through a distance energy is transferred and work is done
What is the formula for work done?
Work done = force x distance
What’s another word for work done ?
Energy transferred
Is a tyre is dragged 5m over the grass, the total pulling force is 340N, what is the work done?
1700J
What is gravitational potential energy?
Gravitational potential energy is the energy that an object has because of its vertical position in a gravitational field
What is the formula for gravitational potential energy?
Gravitational potential energy = mass x gravitational field strength x height
What is kinetic energy?
The energy of movement
What’s the formula for kinetic energy?
Kinetic energy = 1/2 x mass x speed^2
The more it weighs and the faster it is going, the bigger or smaller the kinetic energy?
Bigger
Kinetic energy transferred is also called?
Work done
When a car is braking what does kinetic energy transferred equal?
Work done by brakes
When an object is falling what converts to form kinetic energy?
Potential energy