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Question

phyisics:

you are driving a vehical ( which can deccelarate at a rate of 9.5m/s^2) at a speed of 100 km/hr when you see a parked car 42m ahead.

Assuming that you can stop the moment you saw the car ( 42m ahead ), can you theoretically stop before hitting the parked car

Answer 1

First lets find the time it takes the car to come to a stop

 

Using the equation

Velocity = starting Velocity + acceleration * time

Velocity = 0 when cars stops

starting velocity = 100 km/h ->  100 km/h * 1000km/m * 3600 sec/h  ->  27.7778 m/s

Accel = -9.5 m/s^2

 

0 = 27.8 m/s - 9.5 m/s^2 * time

 

time = 2.9 sec

 

using the equation

x = x_{0 + V0*time + 1/2 accel*time²}

X = 0 + 27.8 m/s * 2.9s - 1/2*9.5m/s² * 2.9s*2.9s

X = 40.7 m

 

The car will come to a stop (42-40.7) m from the parked car 

1.3 meters from parked car