A car moving at a speed of 36 km / h is catching up with a stationary platform. determine the coupling speed, if the weight of the car is 2 tons, the platform is 1 ton.
v1 = 36 kilometers / hour = 10 meters / second – the speed of a moving car;
m1 = 2 tons = 2000 kilograms – wagon weight;
m2 = 1 ton = 1000 kilograms – the mass of a fixed platform.
It is required to determine v2 (meter / second) – the speed of the car and platform after coupling.
To determine the speed of bodies after adhesion, it is necessary to use the following formula (the law of conservation of momentum):
m1 * v1 = (m1 + m2) * v2;
v2 = m1 * v1 / (m1 + m2);
v2 = 2000 * 10 / (2000 + 1000) = 20,000/3000 = 20/3 = 6.7 meters / second (the result has been rounded to one decimal place).
Answer: the speed of the car and the platform after coupling will be 6.7 m / s.
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