A cyclist moving at a speed of 36 km / h brakes to a complete stop. The weight of a cyclist with a bicycle is 70 kg
| April 26, 2021 | education
A cyclist moving at a speed of 36 km / h brakes to a complete stop. The weight of a cyclist with a bicycle is 70 kg. What is the work of the frictional force during braking? Acceleration of free fall is taken equal to 10m / s2.
To calculate the amount of work of the friction force when braking the specified cyclist, we use the formula: Atr = ΔEk = m * (Vn ^ 2 – Vk ^ 2) / 2 = m * Vn ^ 2/2.
Variables: m is the mass of the indicated cyclist with a bicycle (m = 70 kg); Vн – speed before braking (Vн = 36 km / h = 10 m / s).
Calculation: Atr = m * Vn ^ 2/2 = 70 * 10 ^ 2/2 = 3.5 * 10 ^ 3 J.
Answer: When decelerating the said cyclist, the friction force performed work of 3.5 kJ.
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