Newton’s Laws of Physics

Isaac NewtonWas an English physicist and mathematician who is widely recognized as one of the most influential scientists of all time and as a key figure in the scientific revolution.

1. An object at rest stays at rest, an object in motion stays in motion unless an external force is applied

(tape on table flat, then roll it)

2. The force is directly proportional to the acceleration and the mass F=ma

(a 2 000kg car to accelerate at 2m/s2 requires what force? F-newtons, m-kg, a-m/s2)

3. Every action has an equal and opposite reaction

(push the wall and fall back)

All three involve forcesTypes of Forces:

Gravitational- pull from Earth

Magnetic- pull or push from a magnet

Electrical- Static Electricity (hair standing up)

Mechanical- push or pull by touching

Fictional- for against motion

Tensile- tightening

Compressive- pushing together

Rotational- turning

Forces have two parts: magnitude and direction

Magnitude- how much of the force is there

Direction- in which way is the force going

Difference between mass and weight

Weight- force of the mass

Mass- how much matter is in the object

Weight = 9.8 x mass

Gravity

Acceleration of Gravity

g = 9.81 m/s2

FrictionStatic Friction- what prevents an object from

moving

Sliding (kinetic) friction- what slows something down once it's moving.

Static friction is greater- that's why we have ABS breaks

We hate sliding friction, it makes us use more force to move things- we use lubricants to reduce the kinetic friction.

Newton’s 2nd Law of Motion

https://www.youtube.com/watch?v=nO7XeYPi2FU

https://www.youtube.com/watch?v=iwP4heWDhvw

Units of measurementForce = N (Newtons)

Mass = kg (kilograms)

Acceleration = m/s2 (meters per second squared)

Example questionWhat net force is required to accelerate a bike at a rate of 3 m/s2 if the bike has a mass of 2,000kg?

F =

m =

a =

HomeworkPage 39: questions 1, 3, 4