Question

A point moves along a circle having a radius $20cm$ with a constant tangential acceleration $5cm$ $s^{-2}.$ How much time is needed after motion begins for the normal acceleration of the point to be equal to tangential acceleration?

• A. 1 s
• B. 2 s
• C. 3 s
• D. 4 s

Answer 1

Answer: (B)

2 s

$a_t=a_c⟹5=\frac{v^2}{r}$

$\frac{v^2}{20}=5$ gives $v=10cm/s$

Using, $v=u+a_{t}t$, where u=0

$10=0+5t$

$t=2s$