PLease help me answer these questions..?

Question

74. In 2 minutes, a ski lift raises 4 skiers at constant speed to a height of 140 m. The average mass of each skier is 65 kg. What is the average power provided by the tension in the cable pulling the lift?

76. A 63 kg skier coasts up a snow-covered hill that makes an angle of 25 with the horizontal. The initial speed of the skier is 6.6 m/s. after coasting a distance of 1.9 m up the slope, the speed of the skier is 4.4 m/s. a.) Find the work done by the kinetic frictional force that acts on the skis. b.) what is the magnitude of the kinetic frictional force?

Answer 1

In 2 minutes, a ski lift raises 4 skiers at constant speed to a height of 140 m. The average mass of each skier is 65 kg. What is the average power provided by the tension in the cable pulling the lift?

The work done is ( 4 ) ( 65 kg ) ( 9.8 m/s² ) ( 140 m ) = 360,000 J.

The power is thus ( 360,000 J ) / ( 120 s ) = 3000 W.

A 63 kg skier coasts up a snow-covered hill that makes an angle of 25 with the horizontal. The initial speed of the skier is 6.6 m/s. after coasting a distance of 1.9 m up the slope, the speed of the skier is 4.4 m/s. a.) Find the work done by the kinetic frictional force that acts on the skis. b.) what is the magnitude of the kinetic frictional force?

The change in height is ( 1.9 m ) ( sin 25 ) = .80 m.

The work done by gravity is ( 63 kg ) ( 9.8 m/s² ) ( .80 m ) = 490 J.

The loss of kinetic energy is 1/2 ( 63 kg ) ( 6.6² - 4.4² ) = 760 J.

Therefore, the work done by friction is the difference, 270 J.

Answer 2

74.... 260kg*140meters/120 sek=303 kgf-meter/sek=3.9847 hp

=2.973 kw