F=1/2mv2 or F=mv2?

the second equation

Force =ma

Momentum =mv

Kinetic Energy =1/2mv^2

24

Since

f=ma

for a mass m accelerating at a, then assuming an ideal system, we can set the impact force as,

f=m(dv/dt)

for a time interval dt.

For example, a 1 kg mass moving at 500 m/s that hits a 'perfect' steel wall where it uniformly decelerates from 500 m/s to 0 m/s in .02 seconds, has an approximate impact force of 25000 N. Thus, a body which decelerates more quickly has a greater effective impact than one which decelerates more slowly.

This Site Might Help You.

RE:

F=1/2mv2 or F=mv2?

Which is the correct equation for contact force, such as a Karate blow...

Differential equation for force F is:

F = d(m * v) / dt

If the mass is a constant and using the definition of acceleration a as the change in velocity with time, the second law reduces to the more familiar product of a mass and an acceleration:

F = m * a

Since acceleration is a change in velocity with a change in time t, we can also write this equation in the third form shown on the slide:

F = m * (v1 - v0) / (t1 - t0)

F= m*a, E= 1/2mv2 You may want to think of energy as the ability to do work i.e. Force X Distance. If you're asking about a Karate blow, it would seem you want the second equation.

For instance, the energy a bullet imparts upon impact may be measured in ft-lbs.

Neither is right. 1/2* mv^2 is an expression for energy. mv^2 is an expression for momentum. I"m guessing that all you're looking for is F=ma, where F=force, m=mass, a=acceleration.

neither. its E=1/2 mv2

F refers force; ½ mvv or mvv refers energy.

Therefore both equations are wrong. The force x displacement gives the total work done or kinetic energy in this case; it is equal to ½ mvv and not mvv.

force(kinetic energy in this case)=1/2mass*velocity

hope that helps