Question

Ms. Terry Novel is driving down the highway at 26 m/s when the driver sees the light ahead turn yellow. It takes the driver 0.3 s to react and the maximum braking acceleration of her car is 5.3 m/s2. If the light stays yellow for a total of 4 seconds, how far does she travel in this time?

Answer 1

Answer:

67.8 m.

Explanation:

For 0.3 sec which is the response time , he will keep on moving with velocity

undiminished or at 26 m/s .

Distance travelled during this period

= 26 x .3 =7.8 m

For rest of the time ie during 4 - .3 = 3.7 s , he decelerates with deceleration of 5.3 ms⁻²  and initial velocity of 26 m/s

s = u t - 1/2 a t²

s = 26 x 3.7 - .5 x 5.3 x 3.7 x 3.7

= 96.2 - 36.28

= 60 m approx.

Total distance travelled

=60 + 7.8 = 67.8 m.