Physics 2

Created by

Molly Venter

Cards (70)

Topic 5- forces
What is speed
A scalar quantity- has only magnitude
Doesn't have direction
What is velocity 
Describes an object's direction as well as it's speed
Vector quantity- has magnitude and direction
What is the equation for speed
speed= distance/time
assumes that the speed is constant
How do you draw vectors
To add vectors, draw each vector as an arrow one after the other.
The length of the arrow represents the magnitude of a quantity
The direction of the arrow represents the direction of the vector quantity
Pythagoras is used to work out the resultant force
What is the equation for acceleration 
acceleration= change in velocity/ time taken
What is displacement
The distance an object moves in a straight line from a starting point to a finishing point. Vector quantity
What is distance
How far an object moves. Scalar quantity
What is a contact force
Happens when two objects are physically touching
What is a non-contact force 
Happens when objects are separated
What is a normal contact force (e.g.) 
When you push on a table, your hand doesn't move through it. The normal contact force from the table pushes equally on your hand
What is friction
Come about when two surfaces are touching and try to move against each other
What is air resistance 
Comes about when an object moves through air and collides with air molecules
What is tension
The pulling force that a string or cable exerts when someone or something pulls on it
What does a distance-time graph look like
Motion at a constant speed is shown by a straight line
If the line is horizontal, the object is stationary
Speed can be measured by drawing a tangent and calculating the gradient
What does a speed-time graph look like
Motion at a constant speed is shown with a horizontal line
If the object is stationary, the graph will run along y=0
If the object's speed increases, the gradient will be positive
If the object's speed decreases, the gradient will be negative
How can the total distance of a speed-time graph be calculated
Calculate the area under the graph
What is mass 
A measure of the amount of matter that it contains and how difficult it is to change the object's motion- inertia
What is the equation for weight
weight= mass x gravitational field strength
What is the centre of mass 
The point through which an object's weight appears to act
What is a resultant force 
The sum of all of the forces acting on an object. The changes in an object's motion is caused by the resultant force
Resultant force= mass x acceleration
What does Newton's first law state
The velocity of an object will only change if a resultant force is acting on the object.
What does Newton's third law state
Whenever 2 objects interact, the forces that they exert on each other are equal and opposite. If one object exerts a force on another object, then the other object must be exerting a force back
What is inelastic deformation 
An object that will not return to its original shape when the force stops
What is elastic deformation 
An object that will return to its original shape when the force stops
What is limit of proportionality 
The point at which extension is no longer directly proportional to force
What is the equation for Hooke's law
Force= spring constant x extension
What are the stages for investigating Hooke's law- practical
1) Set up the apparatus as shown
2) Measure the original length of the spring
3) Hang different masses on the spring and measure the length of the spring in each case
4) The extension of the spring equals the length with masses minus the original length
5) Plot a graph with extension of the spring on the x axis and force on the y axis
What happens when a spring is compressed
Elastic potential energy is stored in the spring. The energy stored is equal to the work done when stretching it
What is stopping distance 
The distance it take a car to stop in an emergency.
Stopping distance= thinking distance + braking distance
What is thinking distance 
The time it takes for a driver to react to a situation is their reaction time.
What is braking distance
The distance the car travels between the driver applying the brakes and the car stopping
What factors affect thinking distance
Distractions- children, phones
Drugs or alcohol
Tiredness
What factors affect braking distance
Road conditions- wet or icy
The condition of the car
Initial car speed
How is work done on a car affected by speed
The greater, the greater the braking force needed to stop the vehicle in a certain distance. More work needs to be done on the brakes to stop the car
Topic 6- waves
What are waves
Transfer energy from one place to another without transferring matter. Wave motion can be shown by the vibrations of a spring or by water waves
What is a transverse wave 
Causes the particles in the medium to vibrate at right angles to the direction of the wave's motion.
What is a longitudinal wave 
Causes the medium's particles to vibrate in the same direction as the wave's motion
What is the frequency of a wave
The number of times a point on the wave oscillates per second
frequency= number/time