Thread: kinematics problem.

rocket powered sledge accelerates at 35ms-2 and takes 1.6s to pass through a 60m section of a test track. Find the speed at which it entered the section what was its speed when it left?

I think this is the equation to use x=ut + 1/2at2 and than use a=v-u/t to get v ?

a= 35m/s
t= 1.6s
u=?
v=?
x= 60m




please show your working

thanks

Originally Posted by hana_102

rocket powered sledge accelerates at 35ms-2 and takes 1.6s to pass through a 60m section of a test track. Find the speed at which it entered the section what was its speed when it left?

I think this is the equation to use x=ut + 1/2at2 and than use a=v-u/t to get v ?

a= 35m/s
t= 1.6s
u=?
v=?
x= 60m




please show your working

thanks

You are correct, but let me clean this up a bit.

Let the start of the track be your origin and let the +x direction be the direction of the acceleration.

So as you suggested

becomes

and gives you a .

Then
gives your v.

-Dan

When you manipulate the formula to give ‘v’ it does not equal 9.5.
u= 1/2at2 + x / t
??

Originally Posted by topsquark

You are correct, but let me clean this up a bit.

Let the start of the track be your origin and let the +x direction be the direction of the acceleration.

So as you suggested

becomes

and gives you a .

Then
gives your v.

-Dan

You forgot to divide the acceleration term by t when you solved for v, and you have some negation problems:


Okay, let's do some numbers:




So


Gives


and


-Dan