1.
2. Use the figure below for problems 2a, 2b and 2c.
a. If the pulling force P is 150 N and the crate doesn't move, what
is the magnitude of friction force f?
b. If the pulling force P is 200 N and the crate doesn't move, what
is the magnitude of friction force f?
c. If the force P is 250 N, what force of sliding friction f is
necessary to keep the crate sliding at constant velocity?
3. If a force F = (3i - 5j)N acts on a box of goodies
over a displacement of r = ( 2i - 5j) m, find
the work done on the box by the force.
4.The famous Daredevil Gazelle Gi-Gi is giving a
ballet performance on the deck of the USS OutThere aircraft carrier
when she slips on a wet spot and slides off the deck at a speed of 60
m/s. If the deck is 80 meters above the water, and a wave causes the
boat 's deck to lean back at an angle of 37° above the
horizontal, how far does Gi-Gi have to swim to get back to the ship
before the sharks get her if she also has a stiff tailwind of 30 m/s
?
5. A 400 N kid rides a Ferris Wheel at the circus. She is sitting
on a scales, to see how her weight (accrding to the scales ) varies
as she goes around. The Ferris Wheel has a radius of 40 m and she is
moving with a constant speed . If the strap holding her in the seat
must exert a force of 100 N down to hold her in the seat at the top
of the ride,
a) How fast is she moving? (You must draw a FBD to receive any
credit.)
b) What does the scales read at the bottom of the of the Ferris Wheel? (You must draw a FBD to receive any credit.)
6. Determine the reading of each of the scales in the figure
below. (hint: draw a FBD and sum the forces for each pulley and the
100 N block.)
7. A 5-kg penguin sits on top of a 10-kg sled, as in Figure below.
A force of 45 N is applied to the sled down the plane as indicated,
but the penguin attempts to impede the motion by holding onto a cord
attached to a wall The coefficient of kinetic friction between the
moving surfaces is 0.2.
Draw the force diagram for the penguin and identify the Newton's third law reaction force for each force you include.
8. If both shells are fired at the same instant from the
battleship:
a. Which boat gets hit first, A or B ?
b. Why?