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# pound interest arises when interest is added to the principal, so that, from that moment on, the interest that has been added also earns interest. This addition

a body was thrown from certain height and it covered the same distance in the first second and the last three second.what was the time taken by the body to reach the ground?
a)3sec

b)7sec

c)5sec

d)9sec

The question came in NTSE exam conducted by NCERT in National level..
The book name is TATA mc Graw hill
I came to know thiss question from my teacher...
pound interest arises when interest is added to the principal, so that, from that moment on, the interest that has been added also earns interest. This addition of interest to the principal is called compounding. A bank account, for example, may have its interest compounded every year: in this case, an account with \$1000 initial principal and 20% interest per year would have a balance of \$1200 at the end of the first year, \$1440 at the end of the second year, and so on.
In order to define an interest rate fully, and enable one to compare it with other interest rates, the interest rate and the compounding frequency must be disclosed. Since most people prefer to think of rates as a yearly percentage, many governments require financial institutions to disclose the equivalent yearly compounded interest rate on deposits or advances. For instance, the yearly rate for a loan with 1% interest per month is approximately 12.68% per annum (1.0112 − 1). This equivalent yearly rate may be referred to as annual percentage rate (APR), annual equivalent rate (AER), effective interest rate, effective annual rate, and by other terms. When a fee is cha

This question does not make sense: "a body was thrown from certain height and it covered the same distance in the first second and the last three second.what was the time taken by the body to reach the ground?"

Objects accelerate under gravity, so it's not possible for an object to cover the same distance in the first second as the last three seconds. It'll cover more distance per second with every passing second.

Perhaps it's meant to say "a body was thrown from certain height and it covered the same distance in the first three seconds and the last second. what was the time taken by the body to reach the ground?"

First find the distance it travelled in the first three seconds, using (using g as 10m/s/s, v is zero since it's being dropped from rest) d=vt + 0.5gt2

d = 0.5(10)(32)  = 45m

now equate that with the distance travelled in the last second, using the same formula, this time we need to find v:

45 = v(1) + 0.5(10)(12

45 = v + 5

v = 40 m/s

Now use that to find the time, by finding how long it took to reach 40m/s (ie it still has three more seconds till it hits the ground), using v = gt:

40 = 10t

so t = 4 seconds, but this is only the time up until right before the last three seconds, so add 3 seconds, and the total time is 7 seconds.