Understand how forces affect objects Define force Bronze State Newton’s laws of motion Silver Describe whether a force is balanced or not Gold

FORCES When you ride a bike, your foot PUSHES against the pedal. The push makes the wheels of the bike move. When you drop something, it is PULLED to the ground by gravity.

FORCES A FORCE is a PUSH or PULL in a particular DIRECTION. Sometimes, a force is also a twist!

FORCES FORCES AFFECT HOW OBJECTS MOVE. Forces can affect motion in the following ways: They can make objects: START MOVING MOVE FASTER MOVE SLOWER STOP MOVING CHANGE DIRECTION CHANGE SHAPE

There are lots of different types of forces Thrust This can be any driving force, it may be a push or pull, but it could be an engine which forces an object forward. Lift This is the force required to raise an object through a fluid Air resistance This is a force which acts in the air, it can slow objects down when they are moving against it. Or if harnessed could be used to move an object along.

Friction Gravity Upthrust This force acts on objects when they are in contact with a surface, such as the ground. It can be reduced by ensuring both surfaces are smooth. Gravity This force affects every object on Earth. It is a force which pulls everything to the centre of the earth. Upthrust This is an upward force which acts in water, it acts on a object against gravity, and is why certain objects float. Other forces can’t be seen but form fields. Examples of this would be magnetic fields and electromagnetic fields.

Newton’s Laws of Motion If the forces are equal – the object will not change If one force is bigger than other, the object will change Forces always act in pairs

Showing forces We cannot see force, but the effects of the force can. We show the direction of the force as arrows.

Representing Forces The direction of the arrow shows the direction of the force The length of the arrow shows the size of the force

Is there any force acting upon you while your sitting in your chair? YES Which law of motion is this? This is known as a balanced force.

If the table suddenly vanished, the book would fall to the floor. The force pulling the book down is greater than the force pushing it up. This is known as an unbalanced force. Which law of motion is this?

REACTION FORCE GRAVITY The car is not moving. The same forces are acting on it that were acting on the book. REACTION FORCE GRAVITY

What would happen if the car started to move forwards really fast? REACTION FORCE AIR RESISTANCE THRUST GRAVITY

MISCONCEPTION ALERT! If a car is travelling at a CONSTANT SPEED – the forces are balanced so arrows should be the same size.

MISCONCEPTION ALERT! If a car is SPEEDING UP – the forces are unbalanced so the arrows are different sizes.

MISCONCEPTION ALERT! If a car is SLOWING DOWN – the forces are unbalanced so the arrows are different sizes.

Calculating energy used Most electrical appliances use Watts Watts = joules per second If a light bulb has a power rating of 1000W, and is used for 1 minute – you can calculate how much energy is used…

Calculating energy used Watts = joules per second 1000 W 1 minute = 60 seconds 1000W x 60 seconds = 60,000 joules used in that time.

Calculating energy used Watts = joules per second Hair dryer: 700 watts Kettle: 2000 watts Light bulb: 100 watts Hair dryer used for 5 mins Kettle used for 10 mins Light bulb used for 5 hours Remember to convert your times into seconds!!

Act it out… In your groups on your tables – come up with a play to describe at least 2 unbalanced forces 2 balanced forces Use the arrows given to you to show the size of the force. Here are some key words to help you Balanced Unbalanced Speeding up Constant speed Slowing down Level ladders will be on your tables to help you include all the information you need to reach your targets

You must work your way through the levels Bronze Describe the forces acting on the object you have chosen. E.g. Air resistance acting on a car. Silver Describe whether the forces are balanced or unbalanced. E.g. The car is slowing down, so air resistance is larger than thrust. The forces are unbalanced. Gold Explain which of Newton’s laws are involved in your scenario. E.g. As the car is slowing down, the object is changing. This is Newton’s 2nd law of motion. The forces are also acting in pairs, so this is Newton’s 3rd law of motion.