Question

An automobile starting from rest Speeds upto 12 m/s with a constant acceleration of 1.2 m/s²,runs at this speed For a time and finally comes to rest with a deceleration of 1.5 m/s².If the total distance travelled is 366m,Find the total time required

Answer 1

Answer:

Explanation:

u=0m/s

v=12m/s

a=1.2m/s^2

v2=0

-a=-1.5m/s^2

s=366m

t=(v-u)/a

t=12-0/1.2=10 s

s1=ut+1/2(at)^2

s1=1/2*1.2*10*1.2*10=50*1.44=72m

s2=366-72=294m

u2=v=12m/s

s=ut+1/2(at)^2

294=12*t+1/2*2.25*t^2

294=12t+2.25t^2/2

t=11.6(approx.)

Total time=11.6+10=21.6 s

Answer 2

If the total distance travelled is 366m, total time required is 18seconds.

Given:

Initial velocity = u = 0

Final velocity = v = 12m/s.

Acceleration = a = 1.2$m/s^{2}$.

Deceleration = d = 1.5$m/s^{2}$.

Total distance = 366m.

To find:

Total time are required

Solution:

In acceleration journey:

(Initial velocity = 0, Final velocity = 12m/s)

Using equations of motion:  

v = u + at => 12 = 0 + 1.2t => t = 10sec.

Time taken while deceleration:

(Initial velocity = 12m/s, Final velocity = 0m/s)

Using equations of motion:  

v = u + at => 0 = 12 + (-1.5)t => 1.5t = 12 => t = 8sec.

Since, time required while accelerating is 10sec and decelerating is 8sec, total time required is 18sec.

Therefore, if the total distance travelled is 366m, total time required is 18seconds.