A coin is thrown vertically upwards. Assuming air resistance is negligible, which of the following statment is correct?
A. The net force acting on the coin becomes zero when the coin reaches the highest point.
B. The total energy of the coin remains unchanged throughout the motion.
C. The total momentum of the coin remains unchanged throught the motion.
D. The coin is moving at the highest speed at its highest position.
請解答!!! 加埋解釋!!~ 解釋點解其他答案係錯!! ~thx thx thx a lot!!!
Momentum
2008-02-23 7:02 am
回答 (1)
2008-02-23 7:11 am
✔ 最佳答案
答案B.It is because kinetic energy of the coin is converted to potential energy when the coin goes up. Energy is conserved throughout the motion.
A is wrong because at the highest point, the net force acting on the coin is gravity which is not zero. It is the velocity to be zero but not acceleration.
C is wrong because momentum = mass x velocity
the velocity decreases as the coin goes up. therefore, the momentum of the coin also decreases through the motion.
D is wrong because the speed at the highest point is zero.
收錄日期: 2021-04-13 15:11:57
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080222000051KK03995