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A physics professor is pushed up a ramp inclined upward at 30.0° above the horizontal as she sits in her desk chair, which slides on frictionless rollers. the combined mass of the professor and chair is 85.0 kg. she is pushed 2.50 m along the incline by a group of students who together exert a constant horizontal force of 600 n. the professor’s speed at the bottom of the ramp is 2.00 m>s. use the work–energy theorem to find her speed at the top of the ramp.

Answer :

meerkat18
We use two equations for this problem: Newton's 2nd Law of Motion and the linear motion for constant acceleration.

Net force = mass*acceleration

The net force can be determined by first constructing the force body diagram. Be sure to account two forces: weight of professor&desk and the 600 N force.

85(9.81)sin30 + 600sin30 = 85(9.81)(a)
a =0.86 m/s^2

Then we use the other equation:
2ax = v2^2 - v1^2
2(0.86)(2.5) = 2^2 - v1^2
v1 = 2.88 m/s

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