Forces

Question 1

What can forces do to an object?

Answer 1

Forces cannot be seen, but their effects can.

Forces (push or pull on something) can change the SHAPE, SPEED and DIRECTION of travel of an object.

Question 2

Can you describe an example of forces changing: SHAPE

Answer 2

1. If you use your hands to exert a force on a rubber ball, the SHAPE changes.
2. If you hold an elastic band between both pointer fingers, and move hands apart, the force has stretched the band out and this causes it to change SHAPE.

Question 3

Can you describe an example of forces changing: SPEED

Answer 3

1. If you hold a tennis ball at shoulder height and let it go, it drops to the floor. Gravity causes the ball to drop. The SPEED of the ball has changed.
2. If you take your shoe off and place it on the floor, and then give it a gentle push along the floor. After you remove your hand, the shoe slides along the floor. The final motion of the shoe is to stop. Friction changed the SPEED of the shoe.

Question 4

Can you describe an example of forces changing: DIRECTION

Answer 4

1. Turn on an electric fan, blowing air in one direction (acting like artificial wind). Using A4 paper, make a paper aeroplane. Throw the plane towards the fan, at right angles to the air flow:
2. Take the tennis ball and throw it gently upwards. The ball:
   * Does not keep going upwards
   * Gravity is on action
   * The force has changed both SPEED & DIRECTION

Question 5

What two elements do we need to measure any physical quantity in physics?

Answer 5

1. A unit of measurement
2. Apparatus to measure it

Question 6

Describe how a Newton Balance measures forces?

Answer 6

A Newton Balance is a tool that measures force. The unit we use to measure force is called a Newton (N).

How it works:

• Inside the Newton Balance, there’s a spring.
• When you hang something on it, the weight of that object pulls down on the spring.
• The spring stretches, and how much it stretches tells us how strong the force is.
• There’s a scale (like a ruler) on the balance, marked in Newtons.
• The more the object weighs, the more it pulls on the spring, and the higher the number on the scale.

Question 7

Fill in the blanks:

All forces are measured in units of ……………., which have the abbreviation ……………… . A …………….. ………………, sometimes called a ………………. ……………… is used to measure the size of a force.

Answer 7

All forces are measured in units of NEWTONS, which have the abbreviation ‘N’ . A NEWTONS BALANCE, sometimes called a SPRING BALANCE is used to measure the size of a force.