A motorcycle is following a car that is traveling at constant speed on a straigh

Question

A motorcycle is following a car that is traveling at constant speed on a straight highway. Initially, the car and the motorcycle are both traveling at the same speed of 20.5 m/s , and the distance between them is 60.0 m . After t1 = 2.00 s , the motorcycle starts to accelerate at a rate of 7.00 m/s2. The motorcycle catches up with the car at some time t2.

Part A. How long does it take from the moment when the motorcycle starts to accelerate until it catches up with the car? In other words, find t2t1.

Express the time numerically in seconds using three significant figures.

Part B. How far does the motorcycle travel from the moment it starts to accelerate (at time t1) until it catches up with the car (at time t2)? Should you need to use an answer from a previous part, make sure you use the unrounded value.

Answer numerically in meters using three significant figures.

Explanation / Answer

The displacement of the car from t1 is:
Dcar = 60+ 20.5*t m

The displacement of the motorcycle from t1 is:
Dmc = 20.5*t + 0.5*a*t^2 = 20.5*t + 3.5*t^2

The motorcycle catches up with the car when Dcar = Dmc

so 60+ 20.5*t = 20.5*t + 3.5*t^2

so, t = 1.14 m

Distance travelled by motorcycle = displacement of car from t1 to t2
= 60 + 20.5*1.14 m = 83.37 m

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