Question

a car starts from rest and moves along the x axis with constant acceleration of 5 metre per second for 8 seconds if it then continues to move with constant velocity what distance will the car cover in 15 seconds in started from rest​

Answer 1

lets divide the qstn into 2 parts..

(1) the distance it travelled in the frst 8 sec

(2) the distance it travld inte next 4 secs..that is in total 12 sec.

(1) given,

u=0

a=5m/s^2

t=8s

using the eqn s=ut+1/2 at2,

s=0+(1/2)*5*(8^2)

s=160m..................this s d distnce travelled in 8 sec.

now while considering the 2nd part the final velocity in the frst becomes the initial in the sec.

find the final velocity. v=u+at..(not sure abt dis eqn....sry.)

u get v=40m/s.

in the secnd prt it is said that the body moves with uniform velocity. ie a=0

using the eqn s=ut+1/2at2,

u get s=(40*4)+0

s=160m.

thrfore the total distance travelled equals 160+160

=320m.