Question

A constant force acts on a particle and its displacement (y) is related to time (t) as t=sqrt(y) +3
When the velocity is zero, its displacement (in cm) is:
a)0
b)1
c)2
d)3

Answer 1

y(t) = (t-3)^2

Answer 2

I'm not sure if this is correct.
Since velocity = displacement/time
0 = displacement/time
displacement = 0

Answer 3

DIFFERENTIATE IT WITH RESPECT TO TIME AND YOU WILL GET
\[Y=\frac{\frac{dy}{dt}}{4}\]
since give velocity is zero then displacement should also be zero.

Answer 4

@ujjwal @Callisto velocity is not displacement over time but derivative of displacement wrt time. This is not the same, except in case of steady motion.

Answer 5

@ramkrishna how do you get that value of y.. here, dy/dt =4t+6.. isnt it?

Answer 6

If y = (t-3)², then v = 2 (t-3)
v is zero for t=3, so when v=0, then y=0.

Answer 7

I.... am sorry!!!!!!!!

Answer 8

I think the same way @Vincent-Lyon.Fr ..

Answer 9

@Callisto you needn't say sorry for that.. you tried to help and thanks a lot for that..

Answer 10

@Callisto No problem. These are subtleties and lots of problems are solved with displacement /time.

Answer 11

\[y=\sqrt{y}+3\]
\[t-3=\sqrt{y}\]
\[(t-3)*(t-3)=y\]
\[v=2*(t-3)\]
when v=0

t=3

using t=3 in the equation

(t−3)∗(t−3)=y


we get y=0

Answer 12

ok, thanks everybody!

Answer 13

And thanks everyone for correcting my mistakes :)