Two students, Student 1 and Student 2 are on a bridge. They both throw identical rocks into the river below. Student 1 throws a rock straight up at 15.00 m/s, whilst Student 2 throws an identical rock straight down at 15.00 m/s.The rock thrown by Student 2 takes 6.0 seconds to reach the river below. Ignore air resistance. What is the maximum height (m) reached by the rock thrown by Student 1? Give your answer correct to one decimal places.

Question

BlackTom AI · Accepted Answer

The problem involves two rocks thrown from the same height with equal speed but in opposite directions, and asks for the maximum height reached by the rock thrown upward.

First, analyze Student 2's rock to determine the initial height from which both rocks were launched. Treat downward as positive and use s = v0 t + (1/2) a t^2.
- v0 (downward) = 15 m/s, t = 6.0 s, a = g = 9.8 m/s^2.
- Distance to river: H = (15)(6) + 0.5(9.8)(6^2) = 90 + 0.5(9.8)(36) = 90 + 176.4 = 266.4 m.
So the launch height above the river is 266.4 m.

Next, focus on Student 1's rock, which is thrown upward with the same speed 15 m/s. To find the maximum height reached above the launch point, use the kinematic relation v^2 = u^2 + 2 a s, with final velocity v = 0 at the top, u = 15 m/s (upward), and a = -g = -9.8 m/s^2.
- 0 = (15)^2 + 2(-9.8)s
- Solve for s: 0 = 225 - 19.6 s  =>  s = 225 / 19.6 ≈ 11.45 m.
Thus the maximum height above the launch point is about 11.45 m, which rounds to 11.5 m to one decimal place.

In summary, the upward-throw rock rises to approximately 11.5 m above the launch point, while the launch height above the river is 266.4 m (from Student 2’s motion), but the question asks for the maximum height of Student 1's rock above the launch point, yielding about 11.5 m.

查看解析

登录即可查看完整答案

类似问题

A ball is thrown upwards from a bridge at 1.9 m s-1. How much time later does it hit the water 6.7 m below? (Give your answer to one decimal place.)

In a consumer society, many adults channel creativity into buying things

Economic stress and unpredictable times have resulted in a booming industry for self-help products

People born without creativity never can develop it

A product has a selling price of $20, a contribution margin ratio of 40% and fixed cost of $120,000. To make a profit of $30,000. The number of units that must be sold is: Type the number without $ and a comma. Eg: 20000

Which of the following statement regarding cost is correct:

Under the assumptions used in cost-volume-profit analysis, as the activity increases:

更多留学生实用工具

考试浏览器助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单