Physics Kinematics Set #2 w/ Freefall

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14 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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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?


2.

A ball is falling at 20 m/s just be
fore 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.


3.

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?


4.

A worker drops a wrench from the top of a tower 80m tall. With what velocity
does the wrench strike the ground?


5.

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.

a.

What was the initial velocity of the cat?

b.

How high did the car rise in the air?


6.

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 t
he kit
below the climber?


7.

A small fish is dropped by a pelican that is rising steadily at 0.50 m/s.

a.

After 2.5 sec, what is the velocity of the fish?

b.

How far below the pelican is the fish after 2.5 sec?


8.

An armadillo is thrown upward at 35 m/s. How far wi
ll it travel during the next 2
sec?


9.

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 o
f
-
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