Force in kinetic energy/force in momentum =1

[morrobay]

Homework Statement

mass=20
V1=0
V2=10ft/sec
t=2 sec
a=5'/sec/sec
x=10ft
I want to show that the force in momentum and in kinetic energy from above data is the same. With the understanding that simple algebra is being superimposed on calculus.

Homework Equations

K.E.= integral of force over distance= max=mdv/dt (dx) =1/2mv^2
momentum = integral of force over time = mv
force= K.E./change in distance
force=momentum/change in time

The Attempt at a Solution

K.E.= 1000 lb (ft/sec)^2
momentum=200 lb(ft/sec)
The force from kinetic energy = 1000 lb (ft/sec)^2 /10ft =100 lb
The force from momentum = 200 lb (ft/sec)/2 sec= 100 lb
Same force, correct ?

 

[rock.freak667]

I am not sure how your units work, but lbs is a force, so you'd need to divide by acceleration due to gravity to get the mass.

 

[morrobay]

I am not sure how your units work, but lbs is a force, so you'd need to divide by acceleration due to gravity to get the mass.

OK the mass =20 by correction.
Now is the 100 lb force correct ?