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Unformatted text preview: Engineering Mechanics - Dynamics Chapter 14 Solution:
θ = atan ⎛ ⎟
⎜ P = F v sin ( θ ) ⎝l⎠ v= P M g sin ( θ ) v = 0.285 m
s *Problem 14-48
An electric streetcar has a weight W and accelerates along a horizontal straight road from rest
such that the power is always P . Determine how far it must travel to reach a speed of v.
Given: W = 15000 lbf v = 40 ft
s P = 100 hp Solution:
P = Fv = ⎛ W ⎞a v =
⎝g⎠ Guess d = 1 ft Given d
⎮ P dsc = ⎮
⌡ ⎛ W ⎞ v2⎛ d v⎞
⎝ g ⎠ ⎝dsc ⎠ v ⎛ W ⎞ v2 dv
⎝g⎠ d = Find ( d) 0 Problem 14-49
The crate of weight W is given speed v in time t1 starting
from rest. If the acceleration is constant, determine the
power that must be supplied to the motor when t = t2.
The motor has an efficiency ε. Neglect the mass of the
pulley and cable.
W = 50 lbf
v = 10 ft
s t1 = 4 s t2 = 2 s ε = 0.76
g = 32.2 ft
t1 v2 = a t2 a = 2.5 ft
v2 = 5
s 270 d = 180.8 ft ...
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This note was uploaded on 08/16/2011 for the course EGN 3321 taught by Professor Christianfeldt during the Spring '08 term at University of Central Florida.
- Spring '08