Question

9. A ball attached to a string of length 60 cm is spun in a uniform circle with a constant velocity at the rate of 10 rev/s. What is the centripetal acceleration of the ball? 10. A car drives with constant speed of 90 km/h around a roundabout with a diameter of 50 m. What is the centripetal acceleration of the car? 11. The velocity of a particle is v(t) (2-2t) i+ (6t +2) jm/s What is the magnitude and direction of the acceleration of the particle at t 3s?

Answer 1

A)

We know that the centripetal acceleration

a=w^2 ×r. 1rev=2π

here w= 10rev/s =10×2π =20π rad/s, r=60 cm =0.60m

a=(20π)^2×0.60

a=2368.70 m/s^2. Answer

10)

centripetal acceleration a=V^2/r

. Here V=90 km/h =90×1000 /3600 = 25 m/s

. Radius =r =50/2 = 25 m

so a=25^2/25

a=25 m/s^2. Answer