Wow ! This is not simple, Shoot, and I give you a lot of credit and an extra merit badge if you're generally keeping up with it.
I scratched my head for a few minutes, and I think I've got it. Here's what I think is going on:
KE₁ = KE of the box before pushing (1/2) (m) (speed²) = 10 x 2² = 40 joules
KE₂ = KE of the box after pushing 3m (1/2) (m) (speed²) = 10 x 4² = 160 joules
The box gained (160 - 40) = 120 J of kinetic energy.
Now look at the cluttered force diagram. Cat's component of force in the direction of motion is 120N. That's the part of her force that does the work on the box. How much work does she do ?
(force) x (distance) = (120N) x (3m) = 360 joules .
Only 120 J of that energy showed up as increased kinetic energy of the box. The other 240J of her hard-earned work was consumed by friction.
Work of friction = (Friction force) x (distance)
240 J = (friction force) x (3 m)
240 J / 3 m = friction 'force' = 80 N .
I think that's it.
What I did was:
-- Find the work that Cat did.
-- Find the increase in the kinetic energy of the box.
-- The difference ... the 'missing energy' ... was the work done by friction in the same distance.
D. the ability to exercise for longer periods of time
Explanation:
For example, when someone does endurance training, they are stretching their body's ability to do a certain exercise for longer times as opposed to increasing strength.
Hundreds of millions of comet nuclei forming a spherical region that surrounds the solar system is called Oort cloud.
The Oort cloud revolves at tens of thousands of the distance of the earth from the sun.
Comets are the condensed water and dust particles that orbit around the sun with inward helix leaving behind a tail of vapours and vaporize completely as they get closer to the sun during their revolution around it.
They have a nebulous appearance and extremely elongated orbits.
