Monday

July 28, 2014

July 28, 2014

Posted by **Mel** on Sunday, October 2, 2011 at 1:13pm.

a) What is the object's velocity after 15s?

b) If the cliff is 358m high, how long does it take for the object to hit the ground?

- physics -
**hurrdurrbeedooda**, Sunday, October 2, 2011 at 2:02pmAssuming acceleration is the force of gravity.

Vf = Vi + a*t

Vf = 18m/s + 9.81ms^-2 * 15s

Vf = 165.15 m/s

d = Vi*t + 1/2a*t^2

358 = 18m's*t + (1/2)9.81ms^-2 * t^2

Set it to zero:

0 = 4.91ms^-2 * t^2 + 18m/s * t - 358.

Use quadratic formula

t = 6.9s or t = -10.5s

Can't have negative time. Therefore it takes 6.9 seconds.

**Related Questions**

physics - An object is launched horizontally from a cliff. The cliff is 80m high...

physics - two objects are thrown from the top edge of a cliff with a speed of 10...

calculus - Wiley jumps straight up in the air from the edge of a cliff so that ...

Science - Ok so I have to use kinematic equations to solve these. But I make ...

math - A ball is thrown from the edge of a cliff with an initial velocity of 60·...

Physics - Augustine continues to run around. He gets to the park and has the ...

Physics - Augustine continues to run around. He gets to the park and has the ...

physics - Two stones are thrown simultaneously, one straight upward from the ...

physics - Two stones are thrown simultaneously, one straight upward from the ...

Physics - Two stones are thrown simultaneously, one straight upward from the ...