Force - this can change something's speed, direction, or shape. It can be push/repulsive or pull/attractive
Vector - a quantity with magnitude (size)
... [Show More] AND direction
Scalar - a quantity with magnitude (size) but NOT direction
Examples of vectors - force, weight, velocity, acceleration, displacement
Examples of scalars - distance, mass, speed, energy, time
Contact forces - occur when an object is supported by or strikes another object e.g. friction
Non-contact forces - the objects don't physically come into contact, e.g. gravity, magnetic force
Mass - the measure of the amount of matter that anything (including people) are made up of (this is a scalar)
Weight - the measure of the force on an object due to gravity (gravity has a direction, towards the center of the Earth, so this is a vector)
The Earth's gravity - 9.81m/s² (approx.) - it is in m/s² because gravity refers to the acceleration that is put on objects as they are pulled in
Weight - = mass X gravity (can be rearranged) - (also, gravity will always be 9.81 on Earth (above))
Gravity ideas on the moon and Earth - - the gravity of the moon is less than on Earth as the moon has less mass than the Earth.
- One would weigh less on the moon than on Earth, but still have the same mass
- There is no air resistance on the moon as there is no air, so two objects dropped simultaneously, regardless of their weight/mass, would hit the ground simultaneously, as there is no force working against gravity
Resultant forces - the eventual force of two forces acting on one object
- If the forces are acting in the same/opposite directions, just add/subtract
- If they are acting at an angle to each other:
- Draw a scale drawing of all the forces acting
- Measure the distance from tip to tip of the forces; thats the resultant force
- Use a protractor to find a bearing for the force, as force is a vector (so has to have direction too)
Resolving forces - to resolve a force you want to split it into its horizontal and vertical components:
- draw a diagram with the info you have
- label the sides
- find one component using trig
- find the other component using trig [Show Less]