A 70 kg base runner begins his slide into second base when he is moving at a speed of 4.0 m/s

Embry-Riddle Aeronautical University Department of Physical Sciences

Home Work # 8

PS 103 − Technical Physics−I Due Date: October 24, 2014 (Friday)

Name:

Date: October 16, 2014 (Thursday)

Semester: Fall-2014

Section:

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.

• To get the full credit make your work readable to grader. It is student’s responsibility to make his/her thought process clear to the grader. Grader will grade whatever is written on the paper.

• 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 crate of mass 10.0 kg is pulled up a rough incline with an initial speed of 1.50 m/s. The pulling force is 100 N parallel to the incline, which makes an angle of 20.0◦ with the horizontal. The coefficient of kinetic friction is 0.400, and the crate is pulled 5.00 m.

a) How much work is done by gravity?

b) How much mechanical energy is lost due to friction?

c) How much work is done by the 100 N force?

d) What is the change in kinetic energy of the crate?

e) What is the speed of the crate after being pulled 5.00 m?

Question# 2:- A 70 kg base runner begins his slide into second base when he is moving at a speed of 4.0 m/s. The coefficient of friction between his clothes and Earth is 0.70. He slides so that his speed is zero just as he reaches the base. (a) How much mechanical energy is lost due to friction acting on the runner? (b) How far does he slide?

a) How much mechanical energy is lost due to friction acting on the runner?

b) How far does he slide?

Question# 3:- An outfielder throws a 0.150-kg baseball at a speed of 40.0 m/s and an initial angle of 30.0◦. What is the kinetic energy of the ball at the highest point of its motion?

Question# 4:- A 2000 kg car moves down a level highway under the actions of two forces: a 1000 N forward force exerted on the drive wheels by the road and a 950 N resistive force. Use the work—energy theorem to find the speed of the car after it has moved a distance of 20 m, assuming that it starts from rest.

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Embry-Riddle Aeronautical University

Question# 5:- An athlete on a trampoline leaps straight up into the air with an initial speed of 9.0 m/s. Find

a) the maximum height reached by the athlete relative to the trampoline and

b) the speed of the athlete when she is halfway up to her maximum height.

Question# 6:- Problems from the text book

a) 5.21

b) 5.28

c) 5.37

d) 5.38

f) 5.60

g) 5.61

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