Transcript Gravitational Force

Gravitational Force
Gravitational force is the force of attraction
between ALL masses in the universe;
especially the attraction of the earth's
mass for bodies near its surface.
= Gravity
– Gravity runs over any range and affects
anything with mass.
– The force of gravity is different from other
forces, such as friction; the force of gravity
acts even if objects do not touch!
Gravitational Force
Equation
• The force is directly proportional to the product of the two
masses and inversely proportional to the square of the
distance between the point masses:
where: F is the magnitude of the gravitational
force between the two point masses,
• G is the gravitational constant,
• m1 is the mass of the first point mass,
• m2 is the mass of the second point mass, and
• r is the distance between the two point masses.
Gravitational Force
• Gravitational Force rapidly grows
weaker as the distance between two
objects increases.
• If the original distance is tripled, the gravitational
force decreases to one-ninth its original value.
Gravitational Force
• Gravitational force is weaker than other
types of forces, even though it holds the
planets, stars, and galaxies together.
Gravitational Force
• Remember….
– The greater the mass, the stronger
the force
– The greater the distance between two
objects, the weaker the gravitational
force between them.
• Introduction to Gravity - YouTube.mp4
Centripetal Force
• For an object moving in a circle, there
must be an inward force acting upon it in
order to cause its inward acceleration.
Centripetal Force
• The word centripetal means “center seeking”
• Object's moving in circular motion have a
net force acting towards the center
The centripetal force for
uniform circular motion alters
the direction of the object
without altering its speed.
Centripetal Force
• As a car makes a turn, the force of friction acting
upon the turned wheels of the car provides
centripetal force required for circular motion.
Centripetal Force
• As a bucket of water is tied to a string and
spun in a circle, the tension force acting
upon the bucket provides the centripetal
force required for circular motion.
Centripetal Force: Orbit
• As the moon orbits the Earth, the force of
gravity acting upon the moon provides the
centripetal force required for circular
motion.