Circular Motion

Accelerating?Remember that an accelerating object is changing speeds and/or changing directions. Since

the hammer is traveling in a circle

(changing directions) , we know that it is accelerating.Since the hammer

is accelerating, we know that there

must be an unbalanced force

acting on it

If the object is changing directions, there must be acceleration. This means there is an force causing the acceleration. Since the object is turning to the left, an unbalanced force to the left must be occurring

What if the force is turned off?

If the force is turned off, then the object will continue to move in a STRAIGHT line.

It will not turn to the left anymore. It will not turn to the right.

ACCELERATION AROUND THE SUN?

Gravitational Force•Gravitational force – an attractive force that

every object in the universe exerts on every other object in the universe.,

Sir Isaac Newton noticed an apple fall to the ground and reasoned that according to his

observations of objects accelerating, the falling bodies to the Earth is caused by a force (a force

of attraction).

Newton’s Universal Law of Gravitation• Every body attracts every

other body in the universe

• The force is directly proportional to the masses of the two bodies

• The force is inversely proportional to the square of the distance between them.

Factors Related to Gravitational Attraction:

1) Masses of bodies (The higher the mass, the higher the amount of attraction.)

2) Distance between bodies (The greater the distance, the less amount of attraction.)

Gravitational Force Exists between any two masses

Gravitational force attracts all masses to each other. It exists between any two masses regardless of size.

The force of attraction between desks in a classroom is negligibly small relative to the force between the Earth and each desk because of the differences in mass.

• If the gravitational force acts between all masses, why doesn’t the earth accelerate up toward a falling apple?

• It does!

• But, the Earth’s acceleration is so tiny that you cannot detect it. Earth’s mass is so large, and acceleration is inversely proportional to mass, so the Earth’s acceleration is negligible

Equation for calculation of gravitational force between two bodies: