# Physics

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There's 2.

1) A 1200-kg airplane starts from rest and, with a constant average forward acceleration of magnitude 5.0m/s^2, reaches its take off speed in 9.00 s. The runway is 300 m long. What is the planes takeoff speed?

2) A boy is attempting to swim directly across a river. He is able to swim at a speed of .500 m/s relative to the water. the river is 25.0m wide and the boy end up at 50.0m downstream from his starting point. How fast is the current of the river?

• Physics (#1 of 2) -

1) The acceleration rate times the time spend taking off is the takeoff speed. Two of the numbers you were given are not needed to solve the problem. Takeoff does not require the full runway length. It would be dangerous if it did.

• Physics -

Oh I see. So 45m/s

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