Make sure you are familiar with units for
Mass: kilogram (kg)
Distance: metre (m)
Speed: metre per second (m/s)
Acceleration: metre per second squared (m/s^2)
Force: newton (N)
Time: second (s)
Gravity: newton/kilogram (N/kg)
Forces can act on a body to change the velocity, so the speed, direction or both.
Or forces can change the shape of a body, stretching it squishing it or twisting it.
different types of forces include:
Gravitational, weight, friction, electrostatic, air resistance (drag), tension (force in a spring), up thrust, lift, thrust
scalars are quantities with only magnitude (size)
vectors are quantities with magnitude (size) and direction
Force has a magnitude measured in (N) but it also has a direction, a push or a pull, up, down, left or right. So force is a vector.
Forces along a line can combine by addition.
Friction is caused by surfaces rubbing. The force always acts in the opposite direction to motion.
Weight (N)= Mass (kg) x gravitational field strength (N/kg)
gravitational field strength on earth is approx. 10 N/kg and in GCSEs is taken to be 10 N/kg.
Hooke’s law is that extension is directly proportional to force applied. This is shown by the straight line on the force-extension graph. Hooke’s law is obeyed as long as the line is straight.
Elastic behaviour is the ability of a material to recover original shape after the force is removed. in a spring this occurs when the force is lower than the elastic limit. loading and unloading force extension curves can be different as long as it returns to its original shape.
