1.A 2 kg rock is released from rest at a height of 29 m.Ignore air resistance and determine the kinetic energy,gravitational potential energy,and total mechanical energy at each of the following heights:20m; 15m; 5m; 9m.2.A man runs with a speed of 6

来源：学生作业帮助网编辑：作业帮时间：2024/05/15 07:45:53

1.A 2 kg rock is released from rest at a height of 29 m.Ignore air resistance and determine the kinetic energy,gravitational potential energy,and total mechanical energy at each of the following heights:20m; 15m; 5m; 9m.2.A man runs with a speed of 6
1.A 2 kg rock is released from rest at a height of 29 m.Ignore air resistance and determine the kinetic energy,gravitational potential energy,and total mechanical energy at each of the following heights:20m; 15m; 5m; 9m.
2.A man runs with a speed of 6 m/s off a platform that is 10 m above the water.How fast if he moving when he hits the water?Ignore air resistance.

1.A 2 kg rock is released from rest at a height of 29 m.Ignore air resistance and determine the kinetic energy,gravitational potential energy,and total mechanical energy at each of the following heights:20m; 15m; 5m; 9m.2.A man runs with a speed of 6
在29米处刚释放时候的总机械能：
E = mgH = 2kg * 10 m/s^2 * 29 m = 580 焦耳
石头在下落过程中,机械能守恒.因此不论在什么高度总机械能（total mechanical energy）都是 580 焦耳.取重力加速度约等于 10 m/s^2.
在 20 m高度处
重力势能gravitational potential energy
Ep = mgh = 2kg * 10m/s^2 * 20m = 400 焦耳
动能 kinetic energy
Ek = E - Ep = 580 - 400 = 180 焦耳
15 m高度处
Ep = 2 * 10 * 15 = 300 J
Ek = E - Ep = 580 - 300 = 280 J
9 m 高度处
Ep = 2 * 10 * 9 = 180 J
Ek = E - Ep = 580 - 180 = 400 J
5 m 高度处
Ep = 2 * 10 * 5 = 100 J
Ek = E - Ep = 580 - 100 = 480 J

人的水平速度保持不变,垂直方向上的速度设为 V⊥.根据机械能守恒.
(1/2)*m* V⊥^2 = mgH
取重力加速度 g = 9.8 m/s^2
V⊥ = √(2gH) = (2*9.8*10)^(1/2) = 196^(1/2) = 14 m/s
因此落在水面时的总速度大小为
V = (V⊥^2 + V‖)^(1/2) = (14^2 + 6^2)^(1/2)
= 232^(1/2)
= 15.2 m/s

1.Was the mechanical energy of the falling mass conserved?Discuss the possible sources of error.2.When a ball at rest is dropped,can it rebound to a greater height than its original height?3.A 2 kg rock is released from rest at a height of 29 m.Ignor 1.A 2 kg rock is released from rest at a height of 29 m.Ignore air resistance and determine the kinetic energy,gravitational potential energy,and total mechanical energy at each of the following heights:20m; 15m; 5m; 9m.2.A man runs with a speed of 6 1.Welcome back.2.The Crazy Join in RockThis is the rock.This is the Crazy Join in RockRide a cow,Through the street,A policeman Looks at You.Blow a Kiss and Ride away.Do the rock,The crazy rock,The crazy rock,The Crazy Join in Rock.Bake a cake,Catch 英语翻译A difference between MPEG-21 REL and ODRL is that ODRL seems more adapted to actual transactions in the commerce environment,whereas MPEG-21 REL has designs on broader cross-vertical applicability.ODRL's primitives map more directly onto His sister is a member of the rock band.同义句 His sister () () the rock band. rock bit by bit 替换 (eat)Water can damage rock bit by bit after a long time,even though the rock is harder. His sister is a member of the rock band.改为同义句His sister ___ ___ the rock band 英译汉The atmosphere at a rock concert full of students is great.1.Almost every band that played was a rock band,it was loud with guitars and drums2.The atmosphere at a rock concert full of students is great.3.Posters on the student notice boards a big rock Rock and roll is that kind of music.Rock and roll is not always playing by a band performers were 错在哪里,改错. 下列高中英语题为什么这样选,分析一下句子成分.越细越好,1.I don't like rock music.___________at rock concerts is noise and flashing light.A:All there is B:All it is C:What is there D:What is it (选A）2.We can't get the car ___ 英语翻译MeasurementThere are two measurements of a merchant ship’s earning capacity which are of fundamental importance to its design and operation.These are deadweight and tonnage.Deadweight is related to the weight of cargo and tonnage is rel rock Rock rock rock rock rock