Force And Motion – Session 6

Imagine you are playing with a toy car and you push it with your hand. The push you give to the car is called the force. The force is like a special type of push or pull that can make things move or stop moving. For example, when you kick a ball, you are using force to make it move.

Now, think about playing soccer. When you want to kick the ball towards the goal, you use force with your foot. The force you apply to the ball makes it move. That is why the ball flies through the air and hopefully goes into the goal. Look around you and find different things you can use force on. Can you push a chair? Can you pull a book? How about giving a gentle push or pull to the door to open it or shut it? Every time you do that, remember that you are using force to make things move.

Do you know what is more interesting? Force not only makes things move but also helps them stop moving. Imagine you have a ball rolling on the ground, and you want to stop it. You put your hand in front of the rolling ball and gently push against its motion. By doing this, you are applying the force in the opposite direction to the motion of the ball.

The force needed to move something depends on how heavy it is and how quickly it is going to move. Imagine you have two toy cars with different masses. One car is very light, and the other car is heavier. If you push both cars with the same force, the car that is light will move faster because it has less mass. But the heavier car will move slower because it has more mass.

We know that acceleration is how quickly something will speed-up or slow-down. Force depends on the mass of the object and how quickly it moves after applying force. We can also say that the force is equal to the mass multiplied by acceleration of the object.

Suppose you have a toy car, and you want to push it to make it move. Let us use the force formula to figure out how much force you need to apply to make the car move. First, find out how much the toy car weighs. Let us say it weighs two kilograms. So, the mass of the car is two kilograms. Now, you want to know how fast you want the car to accelerate. Let us say you want the car to move at an acceleration of 1m/s².

Now, use the force formula to calculate the force needed to make the car move. We shall multiply the mass of the car with acceleration.So, you need to apply two newtons of force to make the toy car move at an acceleration of 1m/s².

Imagine you apply force on the ball. After applying force, the ball starts moving. After some time the ball stops moving. But why? This is due to friction. Friction is the force that tries to slow-down the car when it is moving. Friction happens when two surfaces, like the ball and the floor, rub against each other. It is like a tiny push-back that the floor gives to the ball. This push-back makes it a little harder for the ball to keep moving smoothly.

Friction plays an important role in our lives. You might be wondering why we need friction. Well, think about it this way. If there was no friction, your ball would slip along the floor uncontrollably. You would not be able to move it around properly. Friction helps your ball stay on the ground and move predictably.

Imagine you are playing soccer on a slippery ground. For example on a rainy day your feet would tend to slip all the time. It would be tough to kick the ball. There are high chances of falling. That is because there is very little friction between your shoes and the slippery ground. But on a regular soccer field, the grass and your shoes create enough friction. This allows you to run, kick, and have fun!.

Friction can also be helpful in other situations. When you walk, the friction between your shoes and the ground prevents you from slipping. It helps you stay balanced and move around safely. Different surfaces have different amounts of friction. When you drag your toy car on a wooden floor, it might feel smoother and glide better. While on the carpet, the toy car will move not move so easily. This is because the friction of carpet is greater than the friction of wooden floor.

We shall now understand the drag force. When you ride a bicycle or run, you feel the air pushing against you. That is called drag force or air resistance. It is like the air that makes you slow-down as you move through it. When you ride your bike really fast, you feel more drag force in comparison to when you ride slowly.

Make a paper plane and throwit with your hand. It will fly-away and reach a point at a distance. Now try to throw a piece of paper in same way. The piece of paper will not reach as far as the paper plane reached. But why? This is due to drag force of the air. Paper plane is designed in a way that it minimizes the drag force of the air. We can say that it feels less drag force. This shape of paper plane is also called a streamline-shape because it reduces the drag force. Meanwhile the piece of paper feels more drag force.

Aeroplanes are also designed in a streamline-shape. Due to the streamline-shape of aeroplanes, they can travel smoothly in the air. On the other hand if we are riding a hot-air-balloon in air, it will experience very high drag force because of it’s shape. It is like air is pushing it backwards.