10. A particle starts from rest, moves with constant
acceleration of 10 m/s2. If it travels 35 m in the nth
second of its motion, then the total distance
covered by the particle in n second is
(1) 20 m
(2) 40 m
(3) 60 m
(4) 80 m
11. A particle moves in a straight line such that its
position is given by x = 5(t-2) +6t2, where x is
in meter and t is in second. The initial velocity of
particle is
(1) Zero
(2) 2 m/s
(3) 5 m/s
(4) 12 m/s
e moving with initial velocity to
Answers
For question 10 as we know distance travelled in nth second is
u+a/2(2n-1)
as u =0
and a=10m/s²
we have
5(2n-1)=35
2n-1=7
2n=8
n=4seconds
now distance trave in n second is
s=ut+1/2at²
as u=o
s=5×4²
s=80m
so for question 10 your answer is d 80m
For question 11make sure your question is correct.what does "e moving with initial velocity to" mean please write it correctly
answer
1...80m is the correct answer
explanation
we know that
Distance travel in nth second is
•••u+a/2(2n-1)
as u =0
and a=10m/s²
we have
5(2n-1)=35
2n-1=7
2n=8
n=4 sec
now,
distance travelled in n second is
s=ut+1/2at²
as u=o
s=5×4^2
s=80m
answer
2.).....5m/s is the correct answer......
explanation
Considering the equation is x = 2 +5t +6t²
x= 6t² + 5t + 2
We know that,
v=dx / dt
So,
v= d(6t² +5t +2) /dt
v= 12t + 5
For, initial velocity substitute t=0;
v= 12(0) +5
v= 5m/sec
So, the initial velocity was 5m/sec