Physics help needed

conorhickey

i need help in how to complete this question:
A dynamite blast at a quarry launches a rock straight upward, and 2.4 s later it is rising at a rate of 14 m/s. Assuming air resistance has no effect on the rock, calculate its speed (a) at launch and (b) 5.9 s after launch.
any help would be great

How about telling us what you've tried so far and we'll give you a helping hand on where to go from there? This isn't a forum for doing your homework. ;-)

conorhickey

im not asking for an answer im looking for a way to do it, im not sure what formulas i should be using

dudara

Look at the information you have

At t = 2.4s, v = 14 m/s

It's travelling straight up, so you should know the rate of (de)acceleration

The question is asking you to find u (initial velocity). Once you have solved for u, they want you to recalculate v when t = 5.9s

Now - take a look at your Newtonian formulae and see which one fits best

conorhickey

ive tryed letting the first velocity equal 0 since it is at rest but that is wrong

conorhickey

Is the inital velocity 9.52?

conorhickey

and b = 48.6?

conorhickey

Disregard last answers inital velocity 37.52 and b= -20.3?