1.1
A baseball is hit straight up into the air. The ball spends exactly
7.0 s in total flight time in the air. Remember that the acceleration
due to gravity is a constant 9.81 m/s2.
Hint: Turn this into two separate motions: One upwards and one
downwards. Be careful with your sign for acceleration.
a) What is the initial upward velocity of the baseball?
b) How high does the ball go?
c) What is the final downward velocity of the baseball?
1.2
A car traveling 60 m/s is 90.0 m from a concrete barricade when
the driver slams on the brakes. If the brakes apply an acceleration
of 15m/s2, opposing the direction of motion and the car hits the
barrier 2.00s later. How fast is the car traveling upon impact?
In a different scenario the driver hesitates for 0.25 seconds before
hitting the brakes. At what speed does he strike the barrier now?
2.1
1) Raindrops fall 1700m from a cloud to the ground. How fast
would the drops be moving when they strike the ground?
Remember that the acceleration due to gravity is a constant
9.81 m/s2.
Is this a realistic answer? Explain.
2) Suppose a rocketship in deep space moves with constant
acceleration equal to 9.8 m/s2, which gives the illusion of normal
gravity during the flight.
(a) If it starts from rest, how long will it take to acquire a speed
0.17 times that of light, which travels at 3.0 108 m/s?
(b) How far will it travel in so doing?
2.2
With what speed must a ball be thrown vertically to rise to a
maximum height of 50 m? How long will it rise in the air?
Sketch graphs of its displacement, velocity and acceleration vs
time. You only need to label critical values on your graphs.
3.1
An automobile increases its speed uniformly from 28 km/h to 60
km/h in 0.67 min. A bicycle rider uniformly speeds up to 32 km/h
from rest in 0.67 min.
Calculate the acceleration of the automobile in m/s.
Calculate the acceleration of the bicycle in m/s.
The head of a rattlesnake can accelerate 50 m/s2 in striking a
victim. If a car could do as well, how long would it take to reach a
speed of 97 km/h from rest?
4.1
1) A hiker travels south along a straight path for 1.5 h with an
average speed of 0.75 km/h and then travels north for 2.5 h with an
average speed of 0.90 km/h. What is the hiker’s displacement for
the total trip?
2) A sports car traveling at 27.8 m/s slows at a constant rate to a
stop in 8.00 s. What is the displacement of the sports car and its
acceleration during this time interval?
4.2
1) A soccer ball is moving horizontally at a speed of 3.0 m/s. It
then undergoes a constant negative acceleration. After 4.0 s, the
ball is moving at 1.5 m/s. What is the ball’s displacement?
2) A kitten pushes a ball of yarn rolling toward it at 1.00 cm/s with
its nose, displacing the ball of yarn 17.5 cm in the opposite
direction in 2.00 s. What is the acceleration of the ball of yarn?