Suppose the bob of the previous problem has a speed of 1.4 m/s when the string makes an angle of 0.20 radian with the vertical. Find the tension at this instant. You can use `costheta=1-theta^2/2 and sintheta=theta` for small theta`.

Answer

A

Explanation

Bob has a veloicyt `1.4 m/sec,` when the string makes and angle of 0.2 radian,
`g0.1 kg, m=100`
`r=1m,v=1.4m/sec`

From the diagram,
`T-mgcostheta=(mv^2)/R`
`rarr T=(mv^2)/r+mgcostheta`
Given `costheta=1/theta^2/2` for small theta`
`:. T=(0.1xx(1.4)^2)/1+(0.1)xx9.8(1-theta^2/2)`
`=0.196+0.98xx(1-2^2/2)`
`=0.196+0.98xx(0.98)`
`0.196+0.9604`
`=1.156N~~1.16N`