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3 years ago

12

A boat is able to move through still water at 20m/s. It makes a round trip to.a town 3km upstream.If the river flows at 5m/s,the

times required for the round trip.is

1 answer:

marishachu [46]3 years ago

8 0

Answer:

the answer is 320 seconds :)

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7Which of the following terms describes how glaciers move?

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(A). The work done by friction in crossing the patch is -637.98 J.

(B). The speed of skier is 10.57 m/s.

Explanation:

Given that,

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Length = 3.50 m

Coefficient kinetic friction = 0.30

Height = 2.5 m

(A) we need to calculate the work done by friction in crossing the patch

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$W=-\mu mg\times l$

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$W=-0.30\times62\times9.8\times3.50$

$W=-637.98\ J$

The work done by friction in crossing the patch is -637.98 J.

(B) we need to calculate the speed of skier

Using conservation of energy

$K.E_{i}+U_{i}-W_{friction}=K.E_{f}+U_{f}$

$\dfrac{1}{2}mv_{1}^2+mgh-\mu mgl=\dfrac{1}{2}mv_{2}^2+U_{f}$

Final potential energy is zero

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Put the value into the formula

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$v_{2}=\sqrt{2\times55.915}$

$v_{2}=10.57\ m/s$

The speed of skier is 10.57 m/s.

Hence, (A).The work done by friction in crossing the patch is -637.98 J.

(B).The speed of skier is 10.57 m/s.

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if you wanted to increase the energy of a wave but you had to leave the wavelength the same what might you do

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