Question

A particle moves along a circle of radius $\left(\frac{20}{\pi }\right)m$ with tangential acceleration of constant magnitude. If the speed of the particle is 80 m/s at the end of the second revolution after motion has begun, the tangential acceleration is

• A. $20m/s^2$
• B. $40m/s^2$
• C. $30m/s^2$
• D. $50m/s^2$

Answer 1

The correct option is B $40m/s^2$

Total distance travelled$=2\pi r\times 2($for 2 revolution)

$⟹S=2\times 2\pi \times \frac{20}{\pi }=800$ ...... (1)

.Now by using the formulae

$v^2-u^2=2aS$

$(80{)}^2=2\ast a\ast 80$ . Since $u=0$ (from Equation 1)

$a=80\times \frac{80}{2}\times 80=40m/s^2$