A guide to what we have covered during this topic....
- Forces can either be 'push' or 'pull', and they work in pairs (have a look at the diagram below).
- Forces are also either balanced or unbalanced, and they are measured using Newtons (N)
- The magnitude of a force is shown on a diagram by the size of the arrow
What are the pairs of forces on this diagram?
- REACTION - WEIGHT are a pair
- DRAG - THRUST are a pair
Can you identify which forces are push, and which forces are pull?
- The car is not moving, OR...
- If its already moving then it will stay at a constant speed.
How do we make an object move?
- Make the forces unbalanced! When forces become unbalanced and object will move, this movement includes acceleration (speeding up), decceleration (slowing down), changing direction.
- When this guy jumps out of the plane the forces on him become unbalanced, and he changes direction and speed.
How do the forces change as you jump out of a plane?!
Gravity is the force that pulls you down towards the Earth, but what is gravity?
- A force that attracts objects with mass towards each other.
- Any object with mass (KG) creates gravity
- The more mass something has, the stronger the gravitational pull it has.
The skydiver has mass (KG) and so he has his own gravitational field, but because the Earth has a much bigger mass it pulls him downwards (really fast!).
The difference between Mass and Weight (follow the link below)
How much would your WEIGHT be on other planets? Use this calculator to find out....
Why are there layers in this picture?
Density is how much MASS there is in a specific AREA. For example, the density of water is 1.0g/cm2.
Honey is the substance with the highest density, and lamp oil has the lowest density.
You can calculate DENSITY using this handy formula triangle
An 800g boulder has a density of 8g/cm3, what is the volume?
- F = FORCE
A birthday present has an area of 2m2 (2 metres squared), and exerts a pressure of 20N/m2 (Newton metres squared), how much does it weigh?
See if you can identify where the pivot is in these diagrams below....