# A heavy ball of mass M is suspended from the ceiling of a car by alight string of mass m (m<<M).  When the car is at rest, the speed of transverse waves in the string is 60 ms−1.  When the car has acceleration, a the waves-speed increases to 60.5ms−1, the value of a, in terms of gravitational acceleration g, is closest to : a.   b.   c.   d.

## Question ID - 50054 :- A heavy ball of mass M is suspended from the ceiling of a car by alight string of mass m (m<<M).  When the car is at rest, the speed of transverse waves in the string is 60 ms−1.  When the car has acceleration, a the waves-speed increases to 60.5ms−1, the value of a, in terms of gravitational acceleration g, is closest to : a.   b.   c.   d.

3537

Answer Key : (a) -

60=

60.5= =

+

g2+a2+g2+g2

a = g

= .

Next Question :

A sample of radioactive material A, that has an activity of 10m Ci(l Ci=3.7  1010decays/s), has twice the number of nuclei as another sample of a different radioactive maternal B which has an activity of 20mCi.  The correct choice for hall-lives of A and B an would then be respectively:

 a. 20 days and 5 days b. 20 days and 10 days c. 5 days and 10 days d. 10days and 40days