Forces Flashcards
What is the difference between weight and mass?
The mass of an object is just the amount of matter in an object. Weight of an object is the force of gravity pulling it towards the centre of the Earth.
What unit is weight measured in?
Newtons.
What is the formula that connects mass, weight and gravity?
weight = mass x gravitational field strength.
What is the gravitational field strength on earth?
10 N/Kg
True or false? Resultant force is the overall force on a point or object?
True
How do you find the resultant force acting on an object?
You just add or subtract the two forces (as long as they are all parallel and act in the same or opposite direction)
What is the resultant force acting on this stationary teapot?
10 N (remember that the unit for forces is newtons, N)
What effect does friction have?
It slows down and stops the moving object.
True or false? Friction is always in the same direction as movement?
False. Friction acts in the opposite direction to force.
What are the names for resistance in fluids?
Air resistance (drag) or water resistance.
What is one factor that can help to reduce drag in fluids?
How streamlined the object is.
Describe the term ‘terminal velocity’. (4 points)
When the object first falls, the force of gravity is much more than the frictional force acting against it. It accelerates. As the speed increases, friction increases. This reduces the acceleration until the frictional force is equal to the accelerating force and then it won’t accelerate anymore. This is its maximum speed, known as terminal velocity.
Explain why on the moon, if a hamster and a feather were dropped simultaneously, they would hit the ground at the same time.
On the moon there is no air resistance. This means that the only force acting upon the objects is gravity and so it would make them fall at the same rate.
Fill in the blanks. Work done to an elastic object is stored as ______ ______ ______.
Elastic potential energy.
Describe the changes in forces of an elastic band as it is stretched out of shape and returns to its original shape again.
Work is done to an elastic object to change its shape. This energy is stored as elastic potential energy. When the force is removed and the object returns to it’s original shape, the elastic potential energy is converted into kinetic energy.
