Physics Kinematics Set #2 w/ Freefall

(remember: velocity-time graphs and other

“pictorial illustrations” are your friends)

  1. A hummer slows down uniformly from 21 m/s to rest in 220m. How long does it take it to stop?
  1. A ball is falling at 20 m/s just before it strikes the floor. It leaves the floor at a speed of 16 m/s traveling up. Find the ball’s average acceleration if the collision lasts 0.04 sec.
  1. A boy sledding down a hill accelerates at 1.4m/s/s/. If he started from rest, in what distance would he reach 7.0 m/s?
  1. A worker drops a wrench from the top of a tower 80m tall. With what velocity does the wrench strike the ground?
  1. A physics student throws a cat straight up into the air. The cat is in the air for 4 sec. before it was caught at its original position.
  2. What was the initial velocity of the cat?
  3. How high did the car rise in the air?
  1. A small first-aid kit is dropped by a rock climber who is descending steadily at 1.9 m/s. After 2.5sec, what is the velocity of the first-air kit, and how far is the kit below the climber?
  1. A small fish is dropped by a pelican that is rising steadily at 0.50 m/s.
  2. After 2.5 sec, what is the velocity of the fish?
  3. How far below the pelican is the fish after 2.5 sec?
  1. An armadillo is thrown upward at 35 m/s. How far will it travel during the next 2 sec?
  1. Ranger Rick in Death Valley National Park is driving at 56 km/hour when a gila monster jumps onto the road 65m ahead of the car. After a reaction time of t sec, the ranger applies the brakes to produce an acceleration of -3.0m/s/s. What is the maximum reaction time allowed if the ranger is to avoid hitting the monster?

Answers:

1) 20.9m 2) a = 900m/s/s 3) d = 17.5m 4) v = 40m/s 5) a) v=20m/s b) d=20m

6) v = 27m/s d = 31m 7) v = 24.5 m/s 8) d = 50m 9) t = 1.6 sec