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Question
When a car driver travelling at a speed of 10 m/s applies brakes and brings the car to rest in 20 s, then retardation will be :
Options
+ 2 m/s2
− 2 m/s2
− 0.5 m/s2
+ 0.5 m/s2
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Solution
+ 0.5 m/s2
The term “retardation” means negative acceleration.
Initial velocity = 10 m/s
Final velocity = 0 m/s
Time taken = 20 s
Acceleration = `"0-10"/20`
⇒ Acceleration = `-0.5 "m/s"^2`
⇒ Retardation = 0.5 `"m/s"^2`
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