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Skid of weight 440 N is stuck in the middle of a circular frozen pond of radius 5 m. He cannot move because the pond is absolutely frictionless. He happens to have his 2.6 kg physics textbook so he looks for a solution to his problem. Unable to find a solution he throws his physics textbook in a fit a rage. Skid throws it at a velocity of 4 m/s directly away from him. After throwing the book, how long does it take Skid to reach the edge of the pond

Respuesta :

Answer:

It takes 21.7 seconds for Skid to reach the edge of the pond.

Explanation:

We can calculate the time that takes Skid to reach the edge of the pond by conservation of linear momentum:

[tex] p_{i} = p_{f} [/tex]

[tex] m_{1}v_{1_{i}} + m_{2}v_{2_{i}} = m_{1}v_{1_{f}} - m_{2}v_{2_{f}} [/tex]  (1)

Where:

m₁: is the Skid's mass

m₂: is the book's mass = 2.6 kg

[tex]v_{1_{i}}[/tex]: is the initial speed of Skid = 0 (he was at rest)

[tex]v_{2_{i}}[/tex]: is the initial speed of the book = 0 (it was at rest)

[tex]v_{1_{f}}[/tex]: is the final speed of Skid =?

[tex]v_{2_{f}}[/tex]: is the final speed of the book = 4 m/s. This value is negative since it is moving in the opposite direction of Skid.

First, we need to calculate Skid's mass.  

[tex] m_{1} = \frac{P}{g} [/tex]

Where:

P: is the weight of Skid = 440 N

g: is the acceleration due to gravity  = 9.81 m/s²

[tex] m_{1} = \frac{P}{g} =\frac{440 N}{9.81 m/s^{2}} = 44.8 kg [/tex]

Now, we can find the speed of Skid from equation (1):

[tex] 0 = 44.8 kg*v_{1_{f}} - 2.6 kg*4 m/s [/tex]          

[tex] v_{1_{f}} = \frac{2.6 kg*4 m/s}{44.8 kg} = 0.23 m/s [/tex]

Finally, the time to reach the edge can be found by using the following equation:

[tex] v_{1_{f}} = \frac{d}{t} [/tex]

Where:

d: is the distance = radius = 5 m

t: is the time =?

[tex] t = \frac{d}{v_{1_{f}}} = \frac{5 m}{0.23 m/s} = 21.7 s [/tex]

Therefore, it takes 21.7 seconds for Skid to reach the edge of the pond.

I hope it helps you!