Please help me in Physic 139. An object moves in the +x direction at a speed of
ID: 1643160 • Letter: P
Question
Please help me in Physic 139.
An object moves in the +x direction at a speed of 40 m/s. As it passes through the origin, it starts to experience a constant acceleration of 3.5 m/s^2 in the -x direction. (a) What will happen next? Please explain your answer: The object will reverse its direction of travel at the origin: The object will keep traveling in the +x direction: The object will travel in the +x direction and then reverses its direction. (b) How much time elapses before the object returns to the origin? (c) What is the velocity of the object when it returns to the origin?
Explanation / Answer
a)the object moves along positive x axis till the velocity becomes zero.and then reverse its direction and travel along negative xaxis.option 3 is correct.
b)time for velocity to be zero
v=u+at1 hereu=40m/s a=-3.5m/s2
0=40-(3.5xt1)
t1=40/3.5=11.43seconds
distance travelled by object in time t1 is
s=ut1+(1/2)at1^2=
s=40(11.43)-(0.5x3.5x11.43^2)=228.5m
t2=time taken to reach origin from 228.5m
t2=2s/a
=(2x228.5)/3.5=130.6seconds
total time taken to reach origin is
t=t1+t2
=11.43seconds+130.6sec
=142 seconds
c)velocity of when it reach origin is
v=at2
=3.5x130.6=457m/s