A block is hung by a string from the inside roof of a van.When the can goes straight ahead at a speed of 28m/s,the block hangs vertically down.But when the van maintains this same speed around an unbanked curve (radius=150m),the block swings toward t
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A block is hung by a string from the inside roof of a van.When the can goes straight ahead at a speed of 28m/s,the block hangs vertically down.But when the van maintains this same speed around an unbanked curve (radius=150m),the block swings toward t
A block is hung by a string from the inside roof of a van.When the can goes straight ahead at a speed of 28m/s,the block hangs vertically down.But when the van maintains this same speed around an unbanked curve (radius=150m),the block swings toward the outside of the curve.Then the string makes an angle A with the vertical.Find angle A.
大概是一辆车打转,半径是150m,平均速度是28m/s.车上系住的罐子也跟着动,问车子以28m/s行走的时候,罐子的角度是多少?
A block is hung by a string from the inside roof of a van.When the can goes straight ahead at a speed of 28m/s,the block hangs vertically down.But when the van maintains this same speed around an unbanked curve (radius=150m),the block swings toward t
这是一个关于向心力的问题,
如果要保持罐子也和车一起运动则需要一向心力,也就是倾斜一个角度α,设物体质量m,向心力F,合力一定在绳子上.
见图
tgα=F/mg
F=mv^2/R代入上式中
tgα=F/mg=V^2/gR=28*28/(150*10)≈0.5227
α=27.5945度
典型的向心力题。
匀速圆周运动的货车，物体的向心力和重力垂直，设物体的质量为m，角度A，关系式为：
tanA=F/mg)
-------------------）=>tanA=v^2/rg=28^2/(150*9.8)≈0.53333=>A=28.072
F=mr^2/r)