Transcript You are on a ride in which the bottom of the ride falls out and you

A 80 kg boy is on a ride in which the bottom
of the ride falls out and he is forced to the
back of the ride. The radius of the ride is 3m
and the coefficient of friction between the
rider and the ride is .3.
a. Draw the forces acting on the rider.
b. What force is causing the rider to keep from
falling?
c. Why does the boy feel that he is pushed up
against the side of the ride?
•B. Friction
•C. Inertia
Ff
mg
Fn
d. Find the minimum velocity necessary to keep the
boy from falling.
Ff
Fn
mg
Universal Law of Gravity analogy to love
Gravity
Love
• Attractive force between two
objects with mass
• Attractive force between two
people
• Closer the objects get the
larger the force
• Two people in love desire to be
close to each other
• Each object experiences the
same force in the direction
towards the other object
• Love is mutual
• The larger the object the
greater the attraction
• Not necessarily the case!
The Universal Law of Gravity
• Fg = G M1*M2
R2
• M1 and M2 mass of the object
• R distance between objects
• G is a universal constant = 6.67 X 10-19m2
kg2
The force that attracts Steve to the earth is
his weight msg
The force Steve exerts on the earth is equal
to the force the earth exerts on Steve
Fse
Fes
Fse = Fes
msg = Gmsme/Re2
Canceling the mass we get
g = Gme/Re2
Fse = msg
Fes = Gms me
Re2
ms = Steve’s mass
g = acc. Of gravity
Me = Earth’s mass
Re = Earth’s radius
G = 6.67x10-11 m^2/kg^2
Calculating g
• g = Gme / Re2
• g =(6.67x10-11m^2/kg^2) (5.97 x 1024kg) / (6.38 x
106m)2
• g = 9.8 m/s2
What happens to g as Steve increases his
distance from the earth? What happens to the
gravitional force?
Fse
H
Re
Fes
If Steve is a distance Re above the earth what is
the new gravitational acceleration (gNew))
Re
Re
Super Steve flies off to a planet that has a mass
four times that of the earth and 3 times the size
What is the gnew its surface.