# A cyclist moving at a speed of 5 m / s bends down and picks up a backpack

A cyclist moving at a speed of 5 m / s bends down and picks up a backpack weighing 10 kg lying on the ground. What will be the speed of a cyclist if his weight with a bike is 90 kg?

To determine the speed of the specified cyclist after the selection of the backpack, we apply the law of conservation of momentum: mw * Vw = V * (mr + mw), from where we express: V = mw * Vw / (mp + mw).

Variables: mw is the total mass of the bike and the specified cyclist (mw = 90 kg); Vв – speed before the selection of the backpack (Vв = 5 m / s); mr is the weight of the backpack (mr = 10 kg).

Let’s perform the calculation: V = mw * Vw / (mp + mw) = 90 * 5 / (10 + 90) = 4.5 m / s.

Answer: After the selection of the backpack, the speed of the cyclist will be 4.5 m / s.

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