# Force and pressure

Get Started. It's Free Force and pressure ## 1. FORCES

### 1.1. Magnetic force

1.1.1. Magnetic force is the force of attraction and repulsion exerted by a magnet

1.1.2. Magnetic force can pass through non-magnetic materials but cannot pass through magnetic material

1.1.3. Like poles repel while unlike poles attract

1.1.4. Magnetic force can act on an object from a distance(pulling distance)

### 1.2. Gravitational force

1.2.1. Gravity is the force of attraction that exists between objects that have mass.

1.2.2. The strength of the pull of gravity between 2 objects depends on their mass and the distance between them.

1.2.3. The greater the mass, the greater the gravitational force

1.2.4. The greater the distance between the 2 objects, the smaller the gravitational force

1.2.5. WEIGHT IS NOT THE SAME AS MASS

1.2.6. gravitational force = weight

### 1.3. Frictional force

1.3.1. Friction is the force that opposes motion between 2 surfaces that are in contact

1.3.2. Friction acts in the direction opposite to motion

1.3.3. The heavier an object, the greater magnitude of force acts on the surface, and hence, the greater the friction.

1.3.4. Less friction is produced on smooth surfaces than on rough surfaces.

1.3.5. Lubricants, such as oil help to reduce the amount of friction produced .This is because they form a protective film over both surfaces, allowing the 2 surfaces to be separated.

1.3.6. Ball bearings are found in moving machines. It is used to reduce the amount of friction produced between moving parts.

1.3.7. Friction produces heat and causes wear and tear.

1.3.8. Friction provides us with grip.

1.3.9. streamlining

### 1.4. What is a force?

1.4.1. a push or a pull

### 1.5. effects of forces

1.5.1. Change the speed of a moving object, either by increasing its speed or slowing it down.

1.5.2. Change the shape or size of an object.

1.5.3. Start an object moving or stop a moving object.

1.5.4. Change the direction of a moving object

1.5.5. Start a stationary object

### 1.6. How can we measure a force?

1.6.1. measured with force-meters (spring balance)

1.6.1.1. extension spring balance

1.6.1.1.1. spring stretches when a force pulls on it

1.6.1.2. compression spring balances

1.6.1.2.1. the spring is compressed when a force acts on it

1.6.2. SI unit is Newton(N)

## 2. Pressure

### 2.1. What is pressure?

2.1.1. Pressure is an expression of force exerted on a surface per unit area.

### 2.2. We can increase pressure by decreasing the area the pressure is acting on

2.2.1. For the same force, when a smaller surface is in contact with an object, the pressure exerted on the object is higher.

### 2.3. SI unit of Pressure is Pascal (Pa) Newton per square meter(N/m^2)

2.3.1. Pa=1 N/m^2

### 2.4. How to calculate pressure?

2.4.1. Pressure=force/area