5 In the diagram below, points \(\mathrm { A } , \mathrm { B }\) and C lie in the same vertical plane. The slope AB is inclined at an angle of \(30 ^ { \circ }\) to the horizontal and \(\mathrm { AB } = 5 \mathrm {~m}\). The point B is a vertical distance of 6.5 m above horizontal ground. The point C lies on the horizontal ground.
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Starting at A , a particle P , of mass \(m \mathrm {~kg}\), moves along the slope towards B , under the action of a constant force \(\mathbf { F }\). The force \(\mathbf { F }\) has a magnitude of 50 N and acts at an angle of \(\theta ^ { \circ }\) to AB in the same vertical plane as A and B . When P reaches \(\mathrm { B } , \mathbf { F }\) is removed, and P moves under gravity landing at C .
It is given that
- the speed of P at A is \(3 \mathrm {~m} \mathrm {~s} ^ { - 1 }\),
- the speed of P at B is \(6 \mathrm {~ms} ^ { - 1 }\),
- the speed of P at C is \(12 \mathrm {~m} \mathrm {~s} ^ { - 1 }\),
- 58 J of work is done against non-gravitational resistances as P moves from A to B ,
- 42 J of work is done against non-gravitational resistances as P moves from B to C .
- By considering the motion from B to C, show that \(m = 4.33\) correct to 3 significant figures.
- By considering the motion from A to B , determine the value of \(\theta\).
- Calculate the power of \(\mathbf { F }\) at the instant that P reaches B .