A sledge loaded with bricks has a total mass of 18.9 kg?

Question

and is pulled at constant speed by a rope inclined at 19.6° above the horizontal. The sledge moves a distance of 20.9 m on a horizontal surface. The coefficient of kinetic friction between the sledge and surface is 0.500.

a) What is the tension in the rope?____N

b)How much work is done by the rope on the sledge?____kj

c)What is the mechanical energy lost due to friction?_____kj

need help on this on guys. Can you show me how to get to the solution. Thanks ;)

Answer 1

Normal force of the sledge is the mass minus the vertical component of the rope tension

18.9*9.81-T sin(19.6)

so friction is
f=0.500*(18.9*9.81-T* sin(19.6))
=.5*(185.4-T*sin(19.6))

since the sledge is moving at a constant speed, the horizontal component of the tension is equal to the friction

cos(19.6)*T=f


2*cos(19.6)*T=185.4-T*sin(19.6)

T=(185.4/(2*cos(19.6)+sin(19.6))

T=83.53 N


b and c are the same since the
work=F*d
the only distance is the horizontal

20.9*83.53*cos(19.6)

1645 J

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