Newton’s Laws of Physics

Isaac Newton Was 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/s 2 requires what force? F- newtons, m-kg, a-m/s 2 )

3. Every action has an equal and opposite reaction (push the wall and fall back)

All three involve forces Types 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/s 2

Friction Static 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 2 nd Law of Motion

Units of measurement Force = N (Newtons) Mass = kg (kilograms) Acceleration = m/s2 (meters per second squared)

Example question What 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 =

Homework Page 39: questions 1, 3, 4