Basic Motion
What formula relates speed, distance and time?
Speed = Distance divided by Time
What is the resultant force acting on a skydiver when they are falling at a constant velocity?
0 N
State the formula for gravitational potential energy.
Energy = m g h
Define a longitudinal wave
A wave where the oscillations/vibrations are parallel to the direction of energy transfer/wave travel
How do we calculate the gradient of a graph?
Change in y divided by change in x (Rise over Run)
Scalar has magnitude (size) only.
Vector has magnitude (size) and a direction.
What is the difference between mass and weight?
Mass is a measure of the amount of matter in an object, measured in kg. Weight is a force when this mass is acted upon by a gravitational field in N.
Describe the energy transfers which take place in a battery powered motor.
Chemical potential in the battery is transferred electrically to kinetic energy in the motor
Give an example of a transverse wave.
What are the two types of practical error?
Random and Systematic (NOT human)
What quantity is equal to the gradient of a displacement-time graph?
The velocity of the object.
Calculate the extension of a spring if it has a spring constant of 20 N/m and the force applied to it is 6.5 N. Assume it hasn't passed the limit of proportionality.
e = 6.5 / 20 = 0.325 m
A box is dragged 6 m across a classroom with a constant force of 270 N. Calculate the work done and state where the energy is transferred to if the box is stationary at the end.
Work done = Force x distance = 270 x 6 = 1,620 J
Transferred to the thermal store of the floor and air.
Wave speed = frequency x wavelength
What is parallax error?
A type of random error caused by measurements not being taken at eye level
A train is travelling North with a velocity of 27m/s. It turns a corner and is now travelling East, without slowing down. What is its velocity?
0 m/s.
If North is a positive direction, South is negative. This means East and West are 0 m/s.
As a runner approaches the end of a race, the push force from their legs is 300 N forwards. If the drag acting on them from air resistance is 450 N backwards, describe the motion of the runner.
The runner will be moving forwards but decelerating, as there is a resultant force of 150 N backwards.
A 750 g water bottle is thrown at 10 m / s across a room. Calculate its kinetic energy.
KE = 0.5 m v2 = 0.5 x 0.750 x 100 = 37.5 J
Calculate the wavelength of a sound wave, travelling at 330 m/s in air, if it has a frequency of 165 Hz.
Wavelength = Speed / Frequency = 330/165 = 2 m
How does a graph show direct proportion?
A straight line through the origin (constant gradient, no y-intercept)
How is a car accelerating shown on a displacement-time graph?
An upwards curving line, getting steeper
State Newton's 3rd Law
Every force has a reaction force which is equal in magnitude and acts in the opposite direction.
A spring, which is following Hooke's Law, is loaded with a 5 N weight. If has a spring constant of 45 N/m, how much elastic potential energy has it stored?
Extension = F / k = 5 / 45 = 0.111 m
Energy = 0.5 k e2 = 0.5 x 45 x 0.0123456 = 0.278 J
In one day (24 hours), 34,560 ocean waves reach the shore. What is the average frequency of the waves?
f = 34,560 / 86,400 = 0.4 Hz
How do we confirm a relationship is inversely proportional?
Take three points on the line, and find the product of the x and y values. It is inverse proportion if the products are equal.