- #1

chwala

Gold Member

- 2,675

- 352

- Homework Statement
- See attached. (question with solution)

- Relevant Equations
- Mechanics

solution is here;

I just need to understand this part ##14.7 = -14.7 =9.8T##... why initial velocity upwards is a negative value? or i am interpreting it wrongly.

...........

In my reasoning,

##v=u+at##

##0=14.7 + (-9.8)t##

## t_1=1.5##

in reverse direction, from top to start point ##T##,

##14.7=0+9.8t##

##t_2=1.5##

##T=1.5+1.5=3##seconds

For second part i have the equation,

particle moving up vertically,

##v^2=u^2+2as##

##0 = 14.7^2 + (2× -9.8s)##

##216.09=19.6s##

##s=11.025##m

and for particle moving downwards,

##v=u+at##

##v=0 + 9.8× 2.5##

##v=24.5##

##24.5^2=0+19.6s##

##s=30.625##m

thus ##s_{total} = 11.025+30.625=41.65≅41.7 ##m

Last edited: