A bullet fired from a rifle begins to fall
as soon as it leaves the barrel.
after air friction reduces its speed.
not at all if air resistance is ignored.

Question

A bullet fired from a rifle begins to fall
         as soon as it leaves the barrel.
	 after air friction reduces its speed.
	 not at all if air resistance is ignored.

anonymous · Answer

I dont understand what its asking for? how would a person know without knowing anything about a gun?

anonymous · Answer

rifle*

anonymous · Answer

@oksuz_ do you have any idea?

anonymous · Answer

i could not the question clearly. But i think, there is not any question here. it says a situation. Gravitation causes the bullet falls. Air molecules gain energy from bullet' kinetic energy. That causes bullet' velocity reduces.

anonymous · Answer

ohh i still dont get it

anonymous · Answer

when you drop a glass of rock, it falls because of gravity. when a bullet fired, it goes both forward and down.

anonymous · Answer

@Isaiah.Feynman I dont understand? you both have different answers?

isaiah.feynman · Answer

Well gravity is the main reason, but it wasn't in the options! so air friction seemed close.

anonymous · Answer

ohh oki

anonymous · Answer

thank you can u stick around for few more questions?

anonymous · Answer

A baseball player hits a ball that soars high into the air. Part A After the ball has left the bat, and while it is traveling upward (at point P in the figure (Figure 1) ), what is the direction of acceleration (Figure 2) ? Ignore air resistance. After the ball has left the bat, and while it is traveling upward (at point in the figure ), what is the direction of acceleration ? Ignore air resistance. (a) (b) (c) figure 1 http://session.masteringphysics.com/problemAsset/1697504/4/Giancoli7.ch3.q05b.jpg figure 2 http://session.masteringphysics.com/problemAsset/1697504/4/Giancoli7.ch3.q05a.jpg

anonymous · Answer

If you ignore air resistance, acceleration is downwards.
Acceleration can *only* be caused by forces. The only force acting on the ball is gravity, which is directed downwards.

If you weren't ignoring air resistance, acceleration would be diagonally down and backwards, because the ball is also slowing down due to the air.

anonymous · Answer

oki thank you.. so if no air resistance it goes down and the acceleration would go down and so will the  direction ?

anonymous · Answer

but how would it go backwards?

anonymous · Answer

The acceleration is directed downwards, but the ball will continue to move upwards until its vertical velocity drops to zero. Then it will start falling. Acceleration means a rate of CHANGE of velocity.

anonymous · Answer

oki i understand that part now but wouldnt it move foward instead of backwards?

anonymous · Answer

Likewise, with air resistance - it will be moving forward but accelerating backwards (ie slowing down)

anonymous · Answer

ohh oki I get it now thank you !