Force multiplication via lever
Suppose you (m = 70kg) want to lift a 200kg (~ 450 lbs) piano onto the bed of a truck.
So you put use a sturdy board over a fulcrum (height of fulcrum is 75cm) one meter away
from the piano. How far away from the fulcrum do
Dynamics Problems
Now lets examine situations where our objects are both translating and rotating. Such
situations call for the use of both N2L for translation, and N2L for rotation, i.e.,
F = ma
= I
Example: Rotating disk
Suppose that a grindstone, whi
Blocks on inclined plane connected to massful pulley
Suppose we have two blocks, m1, and m2 connected to eachother, on an inclined plane.
And suppose that we drape them over a cylindrical pulley, of mass M, radius R. What is
the acceleration of the blocks
riding bike
A common example of connected gears is your bike (or a car which has the same kind of
set up minus the chain). Instead of the gears being in physical contact though, they are
connected by a chain but the result is the same. Consider the follow
Special case: Work done by gravity
Consider special case of gravitational force. Lets in general calculate the work done by
this force. So consider an object moving along some path from one position to the other.
Note that h is just y, so we have,
Example
Work and Energy
Now well investigate the behavior of objects from the perspective of work and energy.
Work performed by constant forces
The first part of the work-energy equation (which well get to momentarily) is work. The
scientific definition of work i
Static Equilibrium
To specify that an object is not moving, it is not enough to say that the sum of the forces
acting on it are zero. For consider the following example,
Clearly the net force on the board is 0. And so the board will not translate anywhere
Example: Egyptian temple
Consider that youre building a temple. So you put two posts in the ground and place the
lintel beam (m = 5000 kg) across them, arranged as follows, with the lintel cantilevered
over the right post. What are the forces F1 and F2 th
Ladder Problem
Suppose a person is standing on a uniform ladder with mass (m = 20kg) which is leaning
against a wall. If the wall is frictionless, and the coefficient of static friction between the
floor and the ladder is s = 1.2, how high can the person
Yo-yo
Suppose you have a 0.25kg yo-yo shaped like a disk with diameter 5cm. If you let it
unwind down the string, what will be its acceleration?
to find out, we draw the forces acting on it and use the force/torque equations.
Orienting our y-axis downward