A) a ball striking a wall, in which the force of the ball on the wall is equal to the force of the wall on the ball
B) a gas balloon in which the buoyant force is greater than its weight and air resistance
C) a man in a parachute when the air resistance is less than his weight
D) an airplane in horizontal flight when the thrust of the engine is equal to the drag of the air
2007-06-22 11:14:43 · 9 answers · asked by Cara 4 in Science & Mathematics ➔ Chemistry
This is just a wild guess, but here goes:
A) If the ball strikes the wall and the forces are equal, will the ball bounce off the wall (only other options are for it to go through it or stick to it).
If it goes through it, it is not likely to accelerate - it may even decelerate. If it sticks to it, then it definitely isn't going as fast as it was and certainly isn't going faster. That's a deceleration.
If it bounces, then it has come to a stop and is once again accelerating, but in the opposite direction. I don't know if that counts or not, but would guess that it does.
B) If buoyancy is greater than weight and air resistance then the balloon would be expected to float. If it were released from a standstill then I would expect it to accelerate. If it were already moving to start with it would probably still accelerate since the higher it goes, the less air pressure there is to deter it's progress.
C) If the air resistance is less than his weight then gravity is going to pull him downward and yes acceleration due to gravity should occur.
D) If the airplane is flying horizontally, then it isn't affected by either a decrease or increase in either the air pressure or the pull of gravity. If the thrust equals the drag then there is no force greater than another to change its acceleration. It sounds like a stable situation to me. So, I would choose this as the answer.
2007-06-22 11:28:14 · answer #1 · answered by my 2 cents 4 · 2⤊ 0⤋
I think its "C"; not "D". If you have a plane with forward thrust just equal to drag of the air I don't think it will be going fast enough to create lift so it will accerarate downwards! (maybe this is a trick question. I base this on the fact that people are able to jump out of a plane at many thousands of feet with a parachute and survive. I think the parachute reaches its terminal velocity (fairly low) and stays at that speed the rest of the way to the ground.
2007-06-22 11:23:08 · answer #2 · answered by Flying Dragon 7 · 0⤊ 0⤋
acceleration will occur when there is a net force acting to the body
The secret here is greater and less in selection B & C
all the rest are equal
answer : its. . . B & C
2007-06-22 11:26:45 · answer #3 · answered by CPUcate 6 · 0⤊ 0⤋
D. Thrust and drag when equal will mean no exceleration.
2007-06-22 11:19:33 · answer #4 · answered by Holmes C 2 · 0⤊ 0⤋
I know this is a "Are you smarter then a fifth grader" question.
D of course.
2007-06-22 11:23:27 · answer #5 · answered by redhotboxsoxfan 6 · 0⤊ 0⤋
D obv
2007-06-22 11:24:43 · answer #6 · answered by Kyle M 2 · 0⤊ 0⤋
D. There is no push nor pull.
2007-06-22 11:21:37 · answer #7 · answered by Burberry_Chick 2 · 0⤊ 0⤋
the balloon cool........Q
2007-06-23 05:37:51 · answer #8 · answered by Immortal lestat 2 · 0⤊ 0⤋
A....
2007-06-22 12:26:29 · answer #9 · answered by Anonymous · 0⤊ 0⤋