Ratio of kinetic energy for objects at 5m/s and 25m/s

[chris.hart]

it reads, '' two identical objects move with speeds of 5m/s and 25m/s. what is the ratio of their kinetic energy



so i think i need to use the equation ke=1/2 mv^2
this is how far i got ke=12.5*m and ke=312.5*m

 

[SammyS]

it reads, '' two identical objects move with speeds of 5m/s and 25m/s. what is the ratio of their kinetic energy

so i think i need to use the equation ke=1/2 mv^2
this is how far i got ke=12.5*m and ke=312.5*m

Hello chris.hart. Welcome to PF !

What is the ratio of those two numbers?

How does that ratio compare to the ratio of the two speeds?

 

[chris.hart]

Hello chris.hart. Welcome to PF !

What is the ratio of those two numbers?

How does that ratio compare to the ratio of the two speeds?

i can't know what the ratio is without finishing the arithmetic? or am i missing something

 

[ap123]

Before using any numbers, write out the ratio using symbols and show us what you get.

 

[jhosamelly]

ratio of their KE somehow means that you need to compare them. How does the first one compare to the second.

 

[SammyS]

i can't know what the ratio is without finishing the arithmetic? or am i missing something

I get that (312.5m)/(12.5m) = 25.0 .

That's the ratio of the kinetic energy of the faster object to the the kinetic energy of the slower object.

 

[chris.hart]

thanks guys but i figured out my problem.
id use the formula pe=ke which is the equivalent of mgh * .5mv^2
so i can just simply eliminate the mass on the both sides and solve the equation

 

[aralbrec]

thanks guys but i figured out my problem.
id use the formula pe=ke which is the equivalent of mgh * .5mv^2
so i can just simply eliminate the mass on the both sides and solve the equation

Hmmm potential energy and gravity have nothing to do with this problem.

A ratio of two quantities is just one divided by the other.

 

[lep11]

Since the objects are identical they have the same mass E_k1/E_k2=½mv₁^2/½mv₂^2=v₁^2/v₂^2...

 

[SammyS]

Since the objects are identical they have the same mass E_k1/E_k2=½mv₁/½mv₂=v₁/v₂...

Those velocities should be squared .

 

[lep11]

Those velocities should be squared .

You're right.