The initial velocity of a body is 10 m/s. After 5 s, the velocity of the body is 20 m/s. Its velocity after 7 s is ___ m/s.
(i)18
(ii)24
(iii) 16
(iv) 27
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The initial velocity of a body is 10 m/s. After 5 s, the velocity of the body is 20 m/s. Its velocity after 7 s is ___ m/s.
(i)18
(ii)24
(iii) 16
(iv) 27
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Answer:
its velocity after 7 s is 24 m/s
Given
Initial velocity(u)=10m/s
Final velocity after 5s(v1)=20m/s
Time(t1)=5s
Time(t2)=7s
To find:-
Velocity of the body after 7s(v2)
Solution:-
We know that-----
a=v-u/t
Here----
a= v1-u/t1
a=20-10/5
a=10/5
a=2m/s²
Thus,acceleration of the body is 2m/s².
Now,by using the first equation of motion,we get-----
v2=u+at2
=>v2=10+2×7
=>v2=10+14
=>v2=24m/s
Thus,the velocity of the body after 7s is 24m/s.