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a motor car of mass 1000 kg is moving along a straight line with uniform velocity of 90km/h . Its velocity is slowed down to 18km/h in 2 second by unbalanced external force . Calculate the acceleration and change inmomentum also calculate force . (Please don't give unnecessary answer ) |
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Answer» nfo : A motorcar of mass 1200 kg is moving along a STRAIGHT line with a uniform velocity of 90 km/h. Its velocity is slowed down to 18 km/h in 4 s by an unbalanced external force. To find : the acceleration and CHANGE in LINEAR momentum and also magnitude of force required. solution : initial velocity, u = 90 km/h = 90 × 5/18 = 25 m/s final velocity, v = 18 km/h = 18 × 5/18 = 5 m/s we know, acceleration = change in velocity with respect to TIME. so, acceleration, a = (final velocity - initial velocity)/time taken = (5 - 25)/4 = -20/4 = -5 m/s² change in linear momentum = final linear momentum - initial linear momentum = mv - mu = m(v - u) = 1200 kg × (5 m/s - 25 m/s) = 1200 kg × -20 m/s = -24000 kgm/s magnitude of force required, F = ma = 1200 kg × 5 m/s² [ just taking magnitude of acceleration because we have to find magnitude of force ] = 6000 N |
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