Practise interpreting force diagrams, resultant forces and motion changes, then applying F = ma and W = mg in familiar mechanics contexts.
The diagram shows a child's toy for accelerating steel balls.
This is how the toy works.
- the toy uses three identical steel balls, each with a mass of 4.1 g
- ball A moves towards the magnet
- ball B is in contact with the magnet
- balls B and C are initially at rest and are in contact with each other
- when ball A collides with the magnet, ball C moves away from the magnet
Ball A moves towards the magnet with an initial velocity of 0.15 m/s.
Calculate the initial momentum of ball A.
initial momentum = ............ kg m/s
Ball A is attracted to the magnet.
Explain how this attraction affects the momentum of ball A as it approaches the magnet.
When ball A collides with the magnet, a force of 1.3 N is exerted on ball C for a time of 0.0025 s.
This causes ball C to move away from the magnet.
Calculate the change in velocity of ball C due to this force.
change in velocity = ............ m/s
A ship floats on the sea.
The ship floats because of the forces acting on it.
The upward force acting on the ship is called upthrust.
This force is shown on the diagram.
Draw another labelled arrow on the diagram to show the other vertical force acting on the ship.
Forces are vector quantities.
State what is meant by the term vector quantity.
Give another example of a vector quantity.