Question

A driver is moving at 17.0 m/s when she sees a child on a bike 65m ahead of her. If the car can brake at 4.9 m/s^2 and the drivers reaction time is 1.6 s, can she avoid hitting the child

Answer 1

Answer:

The driver can  avoid the child because at the time she brake 1.6s the car just move 20.928 meters so is far to the 65 meters where the kind is

Distance= 20.928 m

Explanation:

$V_{o} = 17 \frac{m}{s} \\a= -4.9 \frac{m}{s^{2} }\\ t= 1.6 s$

Distance the kid is 65m so the car have to be less in the time she is braking

So to calculated the distance while she is braking

$X_{f} = X_{o} +V_{o}*t + \frac{1}{2} * a *t^{2}\\ X_{f} = 0m +17 \frac{m}{s} *1.6 s + \frac{1}{2} * 4.9 \frac{m}{s^{2} } *(1.6s)^{2}\\X_{f} = 27.2 m+ (-6.272 m)\\X_{f} = 20.928 m$

The distance of the car is less than the distance of the kid in his bike

So she didn't hit him