A trooper drives her car with a constant speed of 21.5 m/s to the east along a s

Question

A trooper drives her car with a constant speed of 21.5 m/s to the east along a straight road. A speeder drives his car to the east on the same road while slowing down at a constant rate. The speeder moves at 15.6 m/s at time t 0, and 7.8 m/s at time t = 8 s. For the entire interval from t = 0 to t = 8 s, the speeder is ahead of the trooper (that is, the speeder is located to the east of the trooper) (a) In the frame of the trooper, what is the speeder's velocity at t-4 s? magnitude direction m/s Select (b) In the reference frame of the trooper, is the speeder's car speeding up, slowing down, or moving with a constant speed at t 4 s? Explain O Speeding up; the magnitude of the velocity of the speeder relative to the trooper becomes larger over time. slowing down; the distance separating the vehicles is reduced by a decreasing amount each second Moving with constant speed; the distance separating the vehicles is uniformly reduced each second. (c) The trooper has a laser ranging device that can determine the distance between the two cars. She finds that the distance is d at time t-2 s and 0.9d at time t3 S. At timet4S, will the distance between the cars be greater than, less than, or equal to 0.Explain. Greater than 0.8d; the speeder's car is slowing down. Less than 0.8d; the speeder moves with increasing speed in the trooper's frame, so position will change by greater and greater amounts over equal time intervals. Equal to 0.8d; the speed of the trooper does not change.

Explanation / Answer

let;'s find the retardation of speeder , a = (15.6-7.8) / 8= 0.975 m/s^2

v at 4 seonds= 15.6 - 0.975 (4) = 11.7 m/s

speeder velocity = 11.7 - 21.5 = 9.8 m/s

direction: towards west

moving with constant speed. teh distance is reduced every second

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