20 kg crate is sliding down a 33 degree ramp. in order for the crate not to spee
ID: 1397060 • Letter: 2
Question
20 kg crate is sliding down a 33 degree ramp. in order for the crate not to speed up to fast, Paul has to pull the crate with an 80N force in the direction shown, while walking down the ramp. there is a 20N kinetic friction exerted by the ramp. The distance along the ramp is 11.68m. the speed of the crate at the begging of the displament is 1.5 m/s.
a)list the name of conservative forces present in the problem
b)list the name of non-conservative forces present in this problem
c) is Emech conserved or not?
d) use the work kinetic energy theorem to determine the speed of the crate at the end of the displacement
e)the displacement takes place within 3.996s. Determine the average or of the weight
Explanation / Answer
a) gravitational force
b) Firctional force and Force applied by Paul
c) No. mechanical energy is not conserved. Becuase some energy is diidpated in the form of heat due to friction.
D) net workdone = m*g*sin(33)*d -F_paul*d*cos(25) - 20*d
= 20*9.8*sin(33)*11.68 - 80*11.68*cos(25) - 20*11.68
= 166.4 J
Apply Wnet = 0.5*m*(v2^2-v1^2)
v2 = sqrt( v1^2 + 2*Wnet/m )
= sqrt(1.5^2 + 2*166.4/20)
= 4.35 m/s
f) a = (v2 - v1)/t
= (4.35 - 1.5)/3.996
= 0.713 m/s^2
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