What is a force? Can you name any forces?

What is a force? A force is a push, pull or twist. A force cannot be seen but you can see how a force affects an object.

Balanced forces There are two wind machines applying forces to the ice skater. The forces acting on the skater are equal in magnitude and opposite in direction. The forces are balanced, so they cancel each other out. The skater does not move.

Unbalanced forces What if only one wind machine is blowing on the skater? The forces acting on her are no longer balanced so she will start to move to the left. Her speed will change – this is called acceleration. Unbalanced forces lead to a change in speed or direction.

Balanced and unbalanced forces 11/11/2018 Reaction Consider a camel standing on a road. What forces are acting on it? These two forces would be equal – we say that they are BALANCED. The camel doesn’t move anywhere. Weight

What factors can affect your speed in a car?

Balanced and unbalanced forces – summary If the forces on an object are balanced: and the object is stationary, it will remain stationary and the object is moving, it will continue to move at the same speed and in a straight line. In other words, the object will continue to do what it is already doing without any change. If the forces are unbalanced, two things can happen: The speed can change. This is called acceleration. The direction of motion can change.

Balanced and unbalanced forces For each picture describe what is happening to the car. Helpful words: Acceleration Deceleration Constant speed Reversing

Speeding up vs. slowing down

Can you run faster on…. A nice sunny day or a A windy day

Facts on Air Resistance 11/11/2018 Air Resistance is the force that acts ___________ anything that moves through the ______: It gets _______ when you move faster: It can be reduced by using a more “__________” (aerodynamic) shape: Streamlining also works when travelling through _______: Words – water, air, larger, against, streamlined

There is another force which can slow you down, can you think of it?

Acceleration, forces, unbalanced, same speed, speed, stay stopped. If the ___________ on an object are balanced: If the object is stopped, it will _______________. If the object is moving, then it will continue to move at the _____________ and in a straight line. In other words, the object will continue to do what it is already doing without any change. If the forces are __________ two things can happen: The __________ will change. The direction of motion will change. This is called _____________. Acceleration, forces, unbalanced, same speed, speed, stay stopped.