HKCEE 1993
An object is thrown vertically upwards from a point A. It travels to the highest point B and then falls back to A. Neglecting are resistance, which of the following statement is / are true?
(1) The total displasment of the object is zero.
(2) The acceleration of the obect is constant throughout the motion
(3) The time for the upward motion is longer than the time for downward motion.
Ans (1) and (3)
PLZ explain why (3) is false. THX
CE level Phy Mechanic Qu. (1)
2008-04-18 7:03 pm
回答 (2)
2008-04-18 7:12 pm
✔ 最佳答案
by x=ut+ 1/2gt^2u=0
x=1/2gt^2
g =constant
x=constant
so t is the same
so (3) is wrong
2008-04-18 7:13 pm
For answers (3), it is false because the displacement is zero. Using the displacement formula, we can conclude that the time has to be the same for both upward and downward motion. Therefore, the statement is false. The displacement is zero because there is no change in position overall.
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