![]() How far can it launch its 60 gram slug into the air if it is shot straight up?ħ.A motor can do 540 J of work in 9.0 seconds. What mass of water can it pump to a height of 4.5 m in one minute?Ħ.A rifle cartridge contains 250 J of energy. What is the frictional force?Ĥ.How much work is needed to lift a 45-Kg box 9.2 m?ĥ.A pump does 4500 J of work in a minute. The work is done against gravity, so the power P isġ.How much work does Fred do exerting 45 N to lift a box 3.2 m?Ģ.What distance will 90 J of energy slide a box against 12 N of frictional force?ģ.Katherine moves a box 7.2 m doing 9 J of work. Estimate the jogger's power output in Watts. The vertical height of the stairs is 4.5m. ![]() How far must a 200-kg pile driver fall if it is to be capable of doing 13,000J of work?Ī 70-kg jogger runs up a long flight of stairs in 4.0s. Since cos 180 o = -1, we see that the force of friction does negative work on the crate. **The angle is 180 o because x and F fr point in opposite directions. The work done by the gravitational (W g) and normal forces (W N) are perpendicular to the displacement (x), and so
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