Assignment for physics
1. A car and a truck are both traveling with a constant speed of 20m/s. The car is 10m behind the truck.
The truck driver suddenly applies his brakes, causing the truck to decelerate at the constant rate of 2m/s. Two seconds later, the driver of the car applies his brakes and just manages to avoid a rear-ended collision.
Question.
Determine the constant rate at which the car decelerated.
Answers
Answer:
20/7 m/s²
Explanation:
A car and truck are both traveling with a constant speed of 20m/s. The car is 10m behind the truck. The truck driver suddenly applied his brakes, causing the truck to decelerate at the constant rate of 2m/s. Two second later the driver of the car applied his brakes and just manages to avoid a rear-end collision. Determine the constant rate at which the car decelerated.
Speed of Truck = 20 m/s
deceleration = 2 m/s²
V² - U² = 2aS
=> 0² - 20² = 2(-2)S
=> -400 = -4S
=> S = 100
Truck goes 100 m forward
0 = 20 -2T => T = 10
Time taken = 10 sec
and Distance between car & Truck was 10 m
Hence 100 + 10 = 110 m
In 2 Sec Car run = 20* 2 = 40 m
Further car run = 110 -40 = 70m
0² - 20² = 2a(70)
=> -400/140 = a
=> -20/7 = a
Car decelerated at 20/7 m/s²