Technical Physics−I
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Embry-Riddle Aeronautical University Department of Physical Sciences
Home Work # 7
PS 103 � Technical Physics�I Due Date: October 15, 2014 (Wednes- day)
Name:
Date: October 10, 2014 (Monday)
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 weight lifter lifts a 350 N set of weights from ground level to a position over his head, a vertical distance of 2.00 m. How much work does the weight lifter do, assuming he moves the weights at constant speed?
Question# 2:- A shopper in a supermarket pushes a cart with a force of 35 N directed at an angle of 25�
downward from the horizontal. Find the work done by the shopper as she moves down a 50 m length of aisle.
Question# 3:- Starting from rest, a 5.00 kg block slides 2.50 m down a rough 30.0� incline. The coe�cient of kinetic friction between the block and the incline is µk = 0.436. Determine
a) the work done by the force of gravity,
b) the work done by the friction force between block and incline, and
c) the work done by the normal force.
Question# 4:- A horizontal force of 150 N is used to push a 40.0-kg packing crate a distance of 6.00 m on a rough horizontal surface. If the crate moves at constant speed, find
a) the work done by the 150 N force and
b) the coe�cient of kinetic friction between the crate and surface.
Question# 5:- A 7.00 kg bowling ball moves at 3.00 m/s. How fast must a 2.45 g Ping-Pong ball move so that the two balls have the same kinetic energy?
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