Posted by **Anil** on Wednesday, July 20, 2011 at 8:30pm.

A partical is projected vertically upward with speed 20 m/s. What will be the time after particle is at a height 15m above the ground( g=15 m/s*s)

- physics -
**bobpursley**, Wednesday, July 20, 2011 at 8:35pm
h=ho+vi*t-1/2 g t^2

15=0+20t-4.9t^2

Put it in the form of a quadratic equation

at^2+bt+c=0 and use the quadratic equation.

- physics -
**Anil**, Wednesday, July 20, 2011 at 9:15pm
If velocity v of particle moving in straight line is related with distance travelled S as v=2(1+S)^1/2. Find the acceleration of the particle.

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**drwls**, Wednesday, July 20, 2011 at 9:26pm
The actual value of g on Earth is 9.8 m/s^2, which is what BobPursley assumed.

I have no idea you were asked to assume g = 15 m/s^2.

Your follow-up question should have been posted separately.

Use a = dV/dt = dV/ds * ds/dt = V* dV/ds

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