If the torque required to loosen a nut
on the wheel of a car has a magnitude of 40.0 N m, what is the minimum
force that must be exerted at the end of a 30.0 cm wrench to loosen the
nut? (Donít forget to convert!)
How (and why!) would the force required
to open the classroom door change if you moved the handle from its present
position to the middle of the door?
Give three examples of objects that have
no mass at their center of mass.
A 400.0 N child and a 300.0 N child sit
on either end of a 2.0 m long seesaw. Where along the seesaw should
the pivot (fulcrum) be placed to ensure rotational equilibrium?
Why would be advantageous to have a low
center of mass as a bicycle rider rounds a turn?
Two children are rolling automobile tires
down a hill. One child claims that the tire will roll faster is one
of them curls up in the tireís center. The other child claims that
will cause the tire to roll more slowly. Explain which is correct
using the concept of moment of inertia.
As Halleyís comet orbits the sun, its distance
from the sun changes dramatically, from 8.8 x 10^10 m to 5.2 x 10^12 m.
If the cometís speed at closest approach is 5.4 x 10^4 m/s, what is its
speed when it is farthest from the sun if angular momentum is conserved?
Why is the moment of inertia of a tether
ball swinging on a rope greater than spinning a stick of equal mass around?
(In other words, why are the formulas different for the two objects?)
Give an example (in words or pictures)
of a tool (or tools) that incorporate each of the following simple machines.
Wheel and axle
Letís say you are using a crowbar to pry
open a sealed wooden chest. It takes 550 N of force at the tip of
the crowbar to break it open when the tip is 0.05 m from the fulcrum.
If you had your hands 0.95 m from the fulcrum, how much force did you need
to use to get to the treasure?
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