Forces y7 Flashcards
What is a force?
A force is something that pushes or pulls to something else.
Explain force in detail.
Forces are pushes or pulls. They are measured in Newtons.
The mass of an object is how much matter it contains.
The weight of an object is the force caused by gravity pulling down on the mass.
Why are things solid? And why do other things float?
When an object rests on a surface such as the ground, its weight is balanced by the reaction force from the ground. The ground pushes up against the object. The reaction force is what you feel in your feet as you stand still. Without this balancing force you would sink into the ground.
Why do books not sink into desks?
The weight of a book lying on a table is balanced by the reaction force from the table top so it therefore doesn’t sink.
How do forces in Newtons work?
The size of the overall force acting on an object is called the resultant force. If the forces are balanced, this is zero. In the example above, the resultant force is the difference between the two forces, which is 100 - 60 = 40 N.
Why friction good?
- friction between our shoes and the floor stop us from slipping
- friction between tyres and the road stop cars from skidding
- friction between the brakes and wheel help bikes and cars slow down
Frictional forces are much smaller on smooth surfaces than on rough surfaces, which is why we slide on ice.
