1.Two man are rotating a large horizontal beam of length 2.50m,that is fixed at its midpoint and can rotate freely about this point.Graham walks forwards and pushes his end of the beam with a force of 316N. Jimmy pushes on the opposite end of the beam with a force of 356N. Both men are walking clockwise around the middle of the beam.
a.Draw a simple diagram representing this situation
b.Describe what will happen to the beam.
c.Calculate the torque acting on the beam.
2.a ball of mass 56g is falling through water. if it accelerates downwards with an acceleration of 1.9m/s2, with what force is the water pushing the ball upwards?
3. A man of mass 72kg is standing on a skateboard on a smooth surface and holding a bal of mass 3.1kg. He throws his ball with a speed of 42m/s. Calculate the speed with which the man recoils.
4.A game at a fairground requires those playing it to shoot targets with a water gun. The water comes out of the gun in a constant stream with a speed of 70m/s. The force exerted by the water on the target is 52N, what mass of water flows out of the gun each second?
5.A body is performing uniform circular motion with a radius of 17cm and an angular speed of 16兀rad/s
a.What can you say about the direction the object is accelerating?
b.What is the time period for this body to complete one full revolution?
c.What is the objects speed?
d.What is its centripetal acceleration?
@吹泡泡的梦幻

汗……虽然不是什么物理大神，但我是物理专业正在努力翻译中

本来要是中文的话没什么问题，一见到英文就头大，我都不知道自己当初怎么过了六级……都是认得的单词，但拼在一起是什么意思呢意思呢思呢呢……

那啥不知道你们重力加速度算的9.8还是10？

第一题ab就你自己答咯。关于力矩的计算：M=(f1-f2)*l/2(*这个是失积，乘号手机打不出来）

第二题，看题目应该没有什么粘滞力阻力的吧……f-mg=ma牛二就可以解决了

第三题是动量守恒，mv=MV

第四题动量定理mv=ft

第五题a没看太懂额，是说物体加速度的方向？那应该是垂直速度指向圆心了。b匀速圆周运动的周期公式T=2兀/w(pi怎么打啊c线速度v=rw,d加速度a=rw2

不知道你们的习惯和国内是不是一样的有不懂的私聊好了