Let F be the magnitude of the frictional force. This force performs an amount of work W on the bullet such that
W = -Fx
where x is the distance over which F is acting. This is the only force acting on the bullet as it penetrates the tree. The work-energy theorem says the total work performed on a body is equal to the change in that body's kinetic energy, so we have
W = ∆K
-Fx = 0 - 1/2 mv²
where m is the body's mass and v is its speed.
Solve for F and plug in the given information:
F = mv²/(2x)
F = (0.00426 kg) (881 m/s)² / (2 (0.0444 m))
F = 37,234.8 N ≈ 37.2 kN
Answer: 72200
Explanation:
First you must find the height for this is on an inclined hill using:
h=Lsin(angle) —> 28.0sin(11.0) = 5.34
Now you would just use the PE equation (mgh) because you are finding ME and when you starting from the top KE=0, showing that what ever answer you get from PE would equal the same for ME.
Using mgh:
m=1380
g=9.80
h=5.34
(1380)(9.8)(5.34)
=72218.16
*Rounding to the 3rd=72200
Hope this helps :)
Answer: c) Positive acceleration describes an increase in speed; negative acceleration describes a decrease in speed.
Hey
On Earth, you can move or you can not move. if you are moving 50 mph that means relative to Earth (not the Andromeda galaxy). When you start moving (accelerating) you are now moving relative to Earth. when you start slowing down (decelerating [most scientists just say you have negative acceleration]) you are starting to match your velocity to Earth's velocity.
Hope it helped and made any sence at all.
Spiky bob your answerer.
