Forces And Motion Flashcards
Name 3 forces
Any 3 out of:
Frictional Force Gravitational Force Tension Force Electrical Force Normal Force Magnetic Force Air Resistance Force Applied Force Spring Force
Explain the effect of forces on an object
A force acting on an object may cause the object to change shape, to start moving, to stop moving, to accelerate or decelerate.
What is the formula that links speed, distance and time?
Speed = distance / time
Describe two ways of reducing friction
Friction can be reduced by using certian material as follows.
(a) Rollers
(b) Talcum powder
(c) Oil, wax, grease
(d) Air cushion
It can also be reduced by making an object streamline or decreasing the weight of the object.
Explain how a parachute works.
When a parachute is opened, it’s fabric expands and air resistance is created. This air resistance is a force which rapidly slows down the parachute, therefore allowing the person attached to land safely.
What is the formula that links pressure, force and area?
Pressure = Force / Area
How do snow shoes help you walk on snow?
When you walk on snow in normal shoes, your weight is distributed only along the length and width of your shoe, so the pressure on the snow is high and you sink into it. Snow shoes work by lowering the pressure that your feet apply to the snow, so that the snow can push back enough to stop your from breaking its surface.
What is the formula that links turning force with distance and force?
Turning force = force x distance
State the law of moments.
When an object is balanced, the sum of the clockwise moments is equal to the sum of the anticlockwise moments.
Force 1 x its distance from pivot = Force 2 x distance from the pivot
Why do we use a spanner instead of our fingers to unscrew a nut?
It is easier to unscrew a nut with a spanner than with your fingers, because the spanner’s long handle increases the turning effect or moment of the force. The size of a moment is equal to the force used times the distance from the pivot on which it acts. If you use a spanner twice as long, you double the moment, and the nut is twice as easy to turn.
