Question

Question 4.17 A stone tied to the end of a string 80 cm long is whirled in a horizontal circle with a constant speed. If the stone makes 14 revolutions in 25 s, what is the magnitude and direction of acceleration of the stone?

Chapter Motion In A Plane Page 87

Answer 1

Length of string = 80cm =0.8m
Stone makes 14 revolutions in 25sec.
Hence, stone makes 14/25 revolution in 1 sec
e.g frequency = 14/25 sec^-1

We know,
Angular speed (ω)= 2π× frequency
= 2π × 14/25
= 28π/25 rad/sec

Now, acceleration (a) = ω²r
where r is the radius { length of string}
Acceleration = 0.8 × {28π/25}²
= 9.91 m/s²

Answer 2

here I am with your answer mate..