How fast is Dale Earnhart�s car moving? by 18EV0q9

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									How fast is Dale Earnhart’s car moving?
Pizza delivery: need Osama’s GPS
            coordinates
    A window washer on a scaffold is hoisting the scaffold up the side of a
 building by pulling downward on a rope, as shown here. If the magnitude of
   the pulling force is 540 N and the combined mass of the worker and the
scaffold combination is 155 kg, how long will it take him to move up by 5 m?
Can Robin Hood escape?
    The drawing shows Robin Hood (mass =
    82 kg) about to escape from a dangerous
    situation. With one hand, he is gripping
    the rope that holds up a chandelier (mass
    = 220 kg). When he cuts the rope where
    it is tied to the floor, the chandelier will
    fall, and he will be pulled up toward a
    balcony above. Ignoring the friction
    between the rope and the beams over
    which it slides, calculate the time it takes
    for him to rise by 4 meters to the balcony
    above.
A monkey clinging to one end of a rope
that passes over a frictionless pulley is
 balanced by a mirror of exactly equal
  weight on the other end of the rope.
 Can the monkey climb up or down to
          escape the image?
    The figure shows a section of an
      airplane cable-car system. The
maximum permissible mass of each car
  with occupants is 2900 kg. The cars,
riding on a support cable, are pulled by
 a second cable attached to each pylon
(support tower); assume the cables are
    straight. What is the difference in
  tension between adjacent sections of
 pull cable if the cars at the maximum
     permissible mass and are being
 accelerated up the 35° incline at 0.83
                  m/s2?
A student from Physics 201 finds that her car is stuck in the sand and
cannot be driven out. Unable to push it out, she ties a strong rope from
the front of the car to a large tree 26 m away and directly in front of the
car. She then pushes on the middle of the rope with a force of 425 N in a
direction perpendicular to the length of the rope. If the midpoint of the
rope is displaced by 1 m, what is the force applied to the car?
Can the rope ever be perfectly
         horizontal?
The tension at which a fishing line snaps is commonly called
the line's "strength.“ Assuming a constant deceleration, what
minimum strength is needed for a line that is to stop a salmon
of weight 85 N in 8.8 cm if the fish is initially drifting at 2.9
                            m/s?
 The Gagarin Cosmonaut Training Center is used to train
 Russian cosmonauts for space missions. If the device can
rotate at 36 rpm and has a radius of rotation of about 20 m,
       what acceleration does the trainee experience?
 Tarzan plans to cross a gorge by
swinging in an arc from a hanging
  vine. If his arms are capable of
 exerting a force of 1100 N on the
rope, what is the maximum speed
he can tolerate at the lowest point
  of his swing? His mass is 70 kg
     and the vine is 4.8 m long.
  CAUTION - DANGEROUS CURVE AHEAD - REDUCE
               SPEED TO 20 MPH

Johnny gauged the coefficient of friction between his tires and the road to be
0.40. Calling on his extensive knowledge of physics and his skepticism of truth
in advertising, he figured that the sign was there to scare, not to protect, and
that he could easily take the turn at 30 mph, a full 10 mph above the posted
speed limit. The turn was a tight one, 50 meters in radius.
1. Did Johnny make it?
2. How far below the true speed limit was the posted speed limit?
3. If there were no friction, the turn would have to be banked. Find the
necessary angle for this banking, in order for Johnny to complete the turn at
the same maximum speed as friction allowed.
The set-up
 A daredevil stunt involves riding a motorcycle around the
vertical inside wall of a cylindrical structure. If the cylinder
  has a radius of 15 m and the coefficient of static friction
between the motorcycle tires and the wall is 1.1, what is the
minimum speed that will keep the motorcycle and the rider
                 from sliding down the wall?
Secret to success
End
A crate starts from rest and slides 8.15 m down a ramp. When
 it reaches the bottom it is traveling at a speed of 5.75 m/s. If
the ramp makes an angle of 22.0° with the horizontal, what is
   the coefficient of friction between the crate and the ramp?
Applet: Incline with friction
  CAUTION - DANGEROUS CURVE AHEAD - REDUCE
               SPEED TO 20 MPH

Johnny gauged the coefficient of friction between his tires and the road to be
0.40. Calling on his extensive knowledge of physics and his skepticism of truth
in advertising, he figured that the sign was there to scare, not to protect, and
that he could easily take the turn at 30 mph, a full 10 mph above the posted
speed limit. The turn was a tight one, 50 meters in radius.
1. Did Johnny make it?
2. How far below the true speed limit was the posted speed limit?
3. If there were no friction, the turn would have to be banked. Find the
necessary angle for this banking, in order for Johnny to complete the turn at
the same maximum speed as friction allowed.
 What angle requires the
 smallest tension force in
overcoming static friction?
 A circus clown weighing 890 N pulls
  vertically downward on a rope that
passes around three pulleys and is tied
  around his feet. If the coefficient of
static friction between the clown's feet
  and the ground is 0.53, what is the
minimum pulling force that the clown
  must exert to yank his feet out from
              under himself?
End
A fish of mass m is suspended by
 a string as shown. The string is
 fastened securely at point C but
will pull loose from the wall at A
 when the string tension exceeds
19 N. What is the maximum mass
 of the fish that can be supported
           by the string?
Suppose that the coefficient of static
friction ms between the rider's clothing
and the canvas is 0.40 and that the
cylinder's radius R is 2.1 m. What
minimum speed v must the cylinder
and rider have if the rider is not to fall
when the floor drops?
Suppose two horses pull horizontally, each with a force F, on
 ropes attached to a tree stump. If the angle between the two
          ropes is 110°, what is the resultant force?
A crate starts from rest and slides 8.15 m down a ramp. When
 it reaches the bottom it is traveling at a speed of 5.75 m/s. If
the ramp makes an angle of 22.0° with the horizontal, what is
   the coefficient of friction between the crate and the ramp?
 A 6-kg monkey climbs up a massless
 rope that runs over a frictionless tree
     limb and back down to a 23-kg
package on the ground. How long will
it take the monkey to reach the branch
  4 m above the ground if it is able to
   just barely lift the package off the
                 ground?

								
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