A force of 72 dyne is inclined to the horizontal at an angle of `60^(@)`. Find the acceleration in a mass of 9 g, which moves in a horizontal direction.

Options

A. `5 cms^(-1)`
B. ` 4 cms^(-1)`
C. `2ms^(-1)`
D. `3 ms^(-1)`

Answer

B

Explanation

(b) Given, F=72 dyne
F=`72xx10^(-5) Nm^(-2)`
`theta=60^(@)`
`m=9g=9xx10^(-3)Kg`
F'=ma
In this case F'`=F=cos60^(@)`
`a=(F')/(m)=(F cos theta)/(9xx10^(-3))`
`=(72xx10^(-5)xx cos 60^(@))/(9xx10^(-3))=8xx10^(-2)xx(1)/(2)`
`=4xx10^(-2) ms^(-1)=4 cms^(-1)`