Question

(Q1)How much work is done when a bucket of mass 1.5kg with 10g of water in it is pulled up from the bottom of a well 8m deep? Take g=9.8m/s2 (a)100.3j(b)2000.5j(c)901.6j(d)453.7j (Q2) A 65kg sprinter completes a 100m race in 9.83s. Calculate the average kinetic energy of the spinter. (a)3.36kj(b)2.11kj(c)34.15kj(d)65.42kj

Answer 1

Q1

1kg = 1000 g

It does not make sense to use a bucket of 1.5kg to pull up 10 g of water. You must mean 10 kg of water.

1.5kg+10kg=11.5 kg
Work done = mgh (in consistent units)
=11.5*9.8*8 j

Q2
The word "average" has been used very vaguely. If it means to calculate the kinetic energy of the sprinter using the average speed, then it would be:
average speed=100m / 9.83 s. =10.1729 m/s
kinetic energy
=mv²/2
=65*10.1729²/2 (approx.) joules

Answer 2

14 Given that the mass and radius of Jupiter are respectively 1 90 1027kg and 7 15 104km, calculate the escape velocity from the surface of the planet

Answer 3

100.3j