Johnny Leong
Dec26-03, 06:57 AM
I would like to answer a Physics question which is about motion.
Question: An object is dropped from a height of 50 m above the ground from a helicopter. How long does the object take to reach the ground and what is its velocity on landing if the helicopter
(a) is at rest,
(b) is ascending with a velocity of 2 m/s,
(c) is descending with a velocity of 2 m/s and
(d) has just ascended to its maximum height and is about to descend at an acceleration 1 m/s-2?
My answer:
(a) Because the helicopter is at rest, when drop the object, the initial velocity of the object is 0 m/s, right? Then I can perform my calculation to find the answers using v = u + at and v2 = u2 + 2as.
(b) In this question, the initial velocity of the object is -2 m/s because the helicopter is ascending with a velocity of 2 m/s.
(c) The initial velocity of the object is 2 m/s because the helicopter is descending with a velocity of 2 m/s.
The steps to find the answers to (b) and (c) are the same as in (a).
(d) Is it right that the initial velocity of the object is also 0 m/s because the helicopter is only about to descend at an acceleration 1 m/s-2? The acceleration should have no effect on the object dropped. Therefore, the answers should be the same as in part (a).
Question: An object is dropped from a height of 50 m above the ground from a helicopter. How long does the object take to reach the ground and what is its velocity on landing if the helicopter
(a) is at rest,
(b) is ascending with a velocity of 2 m/s,
(c) is descending with a velocity of 2 m/s and
(d) has just ascended to its maximum height and is about to descend at an acceleration 1 m/s-2?
My answer:
(a) Because the helicopter is at rest, when drop the object, the initial velocity of the object is 0 m/s, right? Then I can perform my calculation to find the answers using v = u + at and v2 = u2 + 2as.
(b) In this question, the initial velocity of the object is -2 m/s because the helicopter is ascending with a velocity of 2 m/s.
(c) The initial velocity of the object is 2 m/s because the helicopter is descending with a velocity of 2 m/s.
The steps to find the answers to (b) and (c) are the same as in (a).
(d) Is it right that the initial velocity of the object is also 0 m/s because the helicopter is only about to descend at an acceleration 1 m/s-2? The acceleration should have no effect on the object dropped. Therefore, the answers should be the same as in part (a).