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A 40-kg canoe carrying two people is at rest on the surface of a lake. One of the people is a 50-kg person who is sitting 1.5 m to the left of the center of mass (CM) of the canoe. The other person has 90 kg and is sitting 0.5 m to the right of the CM of the canoe.

At one point in time, the two people rearrange themselves so that the 90-kg now sits 1.0 m to the left of the CM of the canoe, and the 50-kg person is sitting 0.75 m to the right of the CM of the canoe.

By how much, and in what direction, did the canoe move as a result of this rearrangement? Ignore any friction between the canoe and the water.

Respuesta :

Answer:

1.67 m towards right

Explanation:

Let the position of the center of mass of the canoe be at the origin

[tex]m_{c}[/tex] = mass of canoe = 40 kg

[tex]x_{c}[/tex] = position of center of mass of canoe = 0 m

[tex]m_{l}[/tex] = mass of person on left = 50 kg

[tex]x_{l}[/tex] = position of center of mass of person on left = - 1.5 m

[tex]m_{r}[/tex] = mass of person on right = 90 kg

[tex]x_{r}[/tex] = position of center of mass of person on right = 0.5 m

Position of center of mass of the system is given as

[tex]x_{cm} = \frac{m_{c} x_{c} + m_{l} x_{l} + m_{r} x_{r}}{m_{c} + m_{l} + m_{r}} \\x_{cm} = \frac{(40) (0) + (50) (- 1.5) + (90) (0.5)}{40 + 50 + 90} \\x_{cm} = - 0.167 m \\[/tex]

After the two people rearrange their positions, we have

[tex]m_{c}[/tex] = mass of canoe = 40 kg

[tex]x'_{c}[/tex] = position of center of mass of canoe

[tex]m_{l}[/tex] = mass of person on left = 50 kg

[tex]x'_{l}[/tex] = position of center of mass of person on left = - 1 m

[tex]m_{r}[/tex] = mass of person on right = 90 kg

[tex]x'_{r}[/tex] = position of center of mass of person on right = 0.75 m

Position of center of mass of the system remains at the same location and is given as

[tex]x_{cm} = \frac{m_{c} x'_{c} + m_{l} x'_{l} + m_{r} x'_{r}}{m_{c} + m_{l} + m_{r}} \\- 0.167 = \frac{(40) x'_{c} + (50) (- 1.5) + (90) (0.5)}{40 + 50 + 90} \\x'_{c} = 1.502 m[/tex]

Distance traveled by the canoe is given as

[tex]d = x'_{c} - x_{c} = 1.502 - (- 0.167)\\d = 1.67 m[/tex]

direction of movement : towards right.

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