KEY WORDS
Friction – a type of force that makes it harder for objects to move.
Force – when you change the velocity (speed) of an object. You can make it faster, slower, stop or start moving.
Balanced forces – when two or more forces that are equal are pushing against each other so nothing happens.
Unbalanced forces – when two or more forces are pushing against each other but one is stronger than the rest, causing movement.
Newtons – These are the units used to measure forces
A Description of Forces
Force is when you push or pull an object to make it move, stop moving, or move faster or slower. Like when you push a shopping cart, that is force. We measure them in Newtons, after the famous scientist who discovered them, Isaac Newton. We can use tools like Newton metres, Spring scales or Force gauges to measure Newtons. We calculate force using the formula: Mass x Acceleration
SIMPLIFIED –
Force changes the velocity of an object
Force Usage
Sometimes you will get two forces pushing against each other, like when you sit on a chair (the force of your weight on the chair and the chair holding you up). In this case, you get two forces pressing up against each other, and a lot of the time nothing can happen. If you were to stand on something small and breakable, like a cheap, small, plastic toy, it could break. So in that case, there would be two forces pressing against each other, but one would be stronger than the other.
But how does this happen?
Well, in the second example, your force was stronger than the other force(s).
In the first example, nothing happened. This was because there was a balance of forces. A balance of forces means that the two (or more) forces cancel each other out. This happens because they are able to apply the same amount of force. This strength is counted in Newtons, after the famous scientist who discovered them, Isaac Newton.
In the second example, because one force was much stronger than the other, you could say it had more Newtons, and the other force couldn’t hold up, so there was an imbalance of forces.
SIMPLIFIED –
Force is measured in newtons.
If two or more forces are pressing against each other and nothing happens, then the forces are balanced, or are applying the same Newtons to each other.
If two or more forces are pressing against each other and movement is happening, then the forces are out of balance, or they cannot apply the same amount of Newtons.
Gravity, Weight and Mass
Mass is essentially just the amount of stuff (matter) that is in an object. And mass, believe it or not, can actually create force. The force it creates is gravity. The larger amount of mass an object has, the more gravity it can create. And the amount of gravity that is being applied to an object decides it’s weight, along with how much mass the other object has, and how far away the objects are. For example, your weight is decided by your mass, the mass of the planet you are currently on, and how close you are to the planet. The sum we use to calculate weight is mass x gravity
Gravity can also change the acceleration of objects when they fall. For example, gravity on Earth can increase the speed of a falling object by about 10 m/s (squared). M/s means metres per second.
Friction
Friction is a force that makes it harder for other objects to move. When something moves (for example, a car), friction tries to slow it down. Friction is caused by the interaction between the surfaces, and the rougher the surfaces, the greater the friction. Friction slows down objects, creates heat, causes wear, and helps us walk without slipping.
But how does it work? Friction happens when two surfaces catch on each other due to tiny ridges and bumps on the surfaces that we may not be able to see.
Because friction can waste energy, we lower its effects using oil or other lubricants. These work by creating a thin, slippery layer between the two surfaces, which reduces friction.
Another way to reduce friction would be to smooth out the two surfaces so they do not get caught on each other.
Finally, we can also use ball bearings to reduce friction. These are smooth metal spheres that roll between the two surfaces, helping them slide past each other more easily.
FRICTION SIMPLIFIED –
Friction is a force that makes it more difficult for other forces to push objects around.
The techniques mentioned (oil, smoother surfaces, ball bearings) can reduce the effects of friction.
SUMMARY
- Force is when you pull or push an object to make it move or not move.
- Mass x acceleration = force
- Forces can be balanced or unbalanced
- If you can get two forces pushing against each other but nothing happens, like when you sit on a chair, and this means the forces are balanced.
- If they are unbalanced, that means that one force is stronger than the other so there will be movement, like if you were to rip a plant out of the ground.
- Mass causes gravity, and the more mass something has the more gravity it has.
- Weight is mass x gravity.
- Friction makes it harder for other forces to move. It is caused from the force between the surfaces.
- Things that can cause less friction are by using lubricants, having smoother surfaces, and to use ball bearings.