hey can u help me with these 2 questions 1. A mover pushes a 6.61 kg box with a
ID: 1781576 • Letter: H
Question
hey can u help me with these 2 questions
1. A mover pushes a 6.61 kg box with a 47.6 N constant horizontal force up a 18.3° ramp that has a height of 1.51 m. If the ramp is assumed to be frictionless, find the speed of the box as it reaches the top of the ramp using work and energy.
2.A 7.60 kg rocket produces a thrust of 400 N. The rocket is pointed upward and the bottom of the rocket is attached to, and is resting on, a spring with a spring constant of 405 N/m. If the spring compressed 0.184 m prior to launch, what is the rocket's speed when the rocket is launched and the spring has stretched 0.239 m?
Explanation / Answer
along the incline
Fnet = F - Fg
work done = Fnet*L
from work energy relation Work = change in KE
Work = (1/2)*m*(vf^2 - vi^2)
(F - Fg)*L = (1/2)*m*(vf^2 - vi^2)
F = 47.6 N
Fg = m*g*sintheta
(47.6 - (6.61*9.8*sin18.3))*1.51 = (1/2)*6.61*(vf^2-0)
the speed at the top of the ramp vf = 3.53 m/s
==========================
2)
work done by gravitational force Wg = -m*g*(y1+y2) = -7.6*9.8*(0.184+0.239) = -31.5 J
work done by thrust WT = T*(y1+y2) = 400*(0.184+0.239) = 169.2 J
work done by elastic force We = (1/2)*k*(y2^2-y1^2) = (1/2)*405*(0.239^2-0.184^2) = 4.71
total work done = change in KE
-31.5 + 169.2 + 4.71 = 1(1/2)*7.6*v^2
speed v = 6.12 m/s <<<------ANSWER
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