A bartender slides a mug of beer along a bar to a customer. The mug starts with a speed of 1.00 m/s, but by the time it reaches the customer's hand, it has slowed to 0.25 m/s. If the filled mug has a mass of 0.850 kg, how much work is done on the mug by kinetic friction as it slides along the bar to the customer?

Question

Physics

Andrea Hurley

1 July, 17:47

A bartender slides a mug of beer along a bar to a customer. The mug starts with a speed of 1.00 m/s, but by the time it reaches the customer's hand, it has slowed to 0.25 m/s. If the filled mug has a mass of 0.850 kg, how much work is done on the mug by kinetic friction as it slides along the bar to the customer?

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Answers (1)

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Antonio Lin · Answer 1

Initial velocity u = 1 m / s

final velocity v =.25 m / s

mass of the mug m =.85

initial kinetic energy

= 1/2 x. 85 x 1 x 1

=.425 J

final kinetic energy

= 1/2 x. 85 x. 25 x. 25

=.0265 J

Loss of kinetic energy

=.425 -.0265 J

=.3985 J

Work done by friction

= -.3985 J (loss of kinetic energy is due to negative work by friction)