Physical Science-Kinematics
1. You are driving down the highway at a constant speed of 100 m/s. You suddenly see a police car and hit the brakes so that the car decelerates at -2 m/s2. Assuming a constant deceleration, how long will it take for the car to slow down to the posted speed limit of 50 m/s?.
answer: 25 s
2. A car accelerates from rest to about 80 m/s along a race track. During this time, the car is able to accelerate 4 m/s2.
a) How much time does it take for the car to speed up to the final speed?
Answer: 20 s
b) How far has the car gone during this time?
Answer: 800 m
3. An airplane must accelerate from rest to about 50 m/s along the runway in order to be able to take off. During the takeoff, the airplane is able to accelerate 4 m/s2.
a) How much time does it take for the airplane to speed up to the take-off speed?
Answer: 12.5 s
b) How long does the runway need to be in order for the airplane to reach this speed?
Answer: 312.5 m
4. A basketball is thrown straight up with an initial speed of 35 m/s.
a) Using the fact that the speed of the ball at the highest point is zero, find how long it takes the ball to reach its highest point.
Answer: 3.5 s
b) How high did the ball go?
Answer: 61.25 m
5. You throw a golf ball off of the top of a building which is 14 m above the ground. The ball is initially thrown 12 m/s horizontally.
a) How long does it take for the ball to hit the ground?
Answer: 1.67 s
b) How far away from the base of the building does the ball hit the ground?
Answer: 20.08 m
6. A pitcher throws a baseball with an initial speed of 50 m/s at a height of 1 meter above the ground. Answer the following questions assuming that the batter misses the ball and there is nothing behind the batter to stop the ball.
a) How long does it take for the ball to hit the ground?
Answer: 0.447 s
b) How far away from the pitcher does the ball hit the ground?
Answer: 22.36 m