A car traveling 95 km h is 210 m

Embry-Riddle Aeronautical University Department of Physical Sciences

Home Work # 2

PS 103 − Technical Physics−I Due Date: Sep 8, 2014 (Monday)

Name:

Date: September 1, 2014 (Monday)

Semester: Fall-2014

WID:

Total point: 10

Important:

• Home work is due in the beginning of the class on the date mentioned above.

• Please note that providing answers without showing any working will not qualify as correct. So to get full points show EACH AND EVERY STEP.

• Please answer all questions neat and clean in as much detail as you can.

• All the conventions followed in the homework are same as that of lectures.

Question# 1:- A person travels by car from one city to another with different constant speeds between pairs of cities. She drives for 30.0 min at 80.0 km/h, 12.0 min at 100 km/h, and 45.0 min at 40.0 km/h and spends 15.0 min eating lunch and buying gas.

a) Determine the average speed for the trip.

b) Determine the distance between the initial and final cities along the route.

Question# 2:- A motorist drives north for 35.0 minutes at 85.0 km/h and then stops for 15.0 minutes. He then continues north, traveling 130 km in 2.00 h.

a) What is his total displacement?

b) What is his average velocity?

Question# 3:- Every year the Earth travels about 109 km as it orbits the Sun. What is Earth’s average speed in km/h?

Question# 4:- A bowling ball traveling with constant speed hits the pins at the end of a bowling lane 16.5 m long. The bowler hears the sound of the ball hitting the pins 2.80 s after the ball is released from his hands. What is the speed of the ball, assuming the speed of sound is 340 m/s?

Question# 5:- A car traveling 95 km/h is 210 m behind a truck traveling 75 km/h. How long will it take the car to reach the truck?

Question# 6:- A car traveling in a straight line has a velocity of +5.0 m/s at some instant. After 4.0 s, its velocity is +8.0 m/s. What is the car’s average acceleration during the 4.0 s time interval?

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Embry-Riddle Aeronautical University

Question# 7:- A truck covers 40.0 m in 8.50 s while smoothly slowing down to a final speed of 2.80 m/s.

a) the truck’s original speed

b) Find its acceleration.

Question# 8:- Determine the stopping distances for an automobile going a constant initial speed of 95 km/h and human reaction time of 0.40 s:

a) for an acceleration a = –3.0 m/s2;

b) for a = −6.0 m/s2.

Question# 9:- A jet plane lands with a speed of 100 m/s and can accelerate at a maximum rate of −5.00 m/s2 as it comes to rest.

a) From the instant the plane touches the runway, what is the minimum time needed before it can come to rest?

b) Can this plane land on a small tropical island airport where the runway is 0.800 km long?

Question# 10:- A ball is thrown upward from the ground with an initial speed of 25 m/s; at the same instant, another ball is dropped from a building 15 m high. After how long will the balls be at the same height?

Question# 11:- A ball thrown vertically upward is caught by the thrower after 2.00 s. Find

a) the initial velocity of the ball and

b) the maximum height the ball reaches.

Question# 12:- A baseball is seen to pass upward by a window with a vertical speed of 14 m/s. If the ball was thrown by a person 18 m below on the street,

a) what was its initial speed,

b) what altitude does it reach,

c) when was it thrown, and

d) when does it reach the street again?