# D3 118

Topics: Force, Kilogram, Mechanics Pages: 2 (627 words) Published: April 18, 2015
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Narayan, Srikanth
MECH 2110 - section 0111
November 11th,Article
20143/6 Problems 169
Chapter
Problem
118
page the
169300-kg
3/118 The
motor3,
unit
A is used
to -elevate
Engineering
Mechanics
(Dynamics)
- 7th
cylinder at a constant rate of 2 m/s. If the power
meter
B
registers
an
electrical
input
of
2.20
kW,
Meriam & Kraige
calculate the combined electrical and mechanical
efficiency e of the system.

Page 1 of 2

ed.

Problem statement: We are given the masses of two
cylinders, one bigger than the other, an velocity for the
bigger one (as shown), and a motor which powers the
motion of the system as shown. The motion is generated
by a given electrical input. We are to utilize the given
information to find the combined electrical and mechanical
efficiency of this system.

100 kg
300 kg

Objective:
A

B

3/119

A

Find the combined efficiency in this system

2 m/s

Methods and assumptions: Our initial approach to this
problem will revolve around finding the power output being
generated. In order to do this, we will need to know the
power that is moving the 300kg cylinder up at a velocity of
Problem 3/118
2 (m/s). We will define a mechanical system consisting of just that cylinder, with a free body diagram
showing
its rest
weight,
the tension
A
1700-kg car
starts from
at position
A and ac-exerted by the pulley system, and the upward velocity. celerates
uniformly
up the incline,
reaching a
However,
the mathematical
representation
of this tension will be impacted by two things: 1) the
speed
100 km/hthat
at position
B. Determine
the
100kgof cylinder
is, on top
of any power
being generated by the motor, aiding in the lifting of
power required just before the car reaches position
the 300kg cylinder; and 2) the two-rope pulley that is holding up the cylinder. Having accounted B and also the power required when the car is...