Amass of 5.00 kg pulls down vertically on a string that is wound around a rod of radius 0.100 m and negligible moment of inertia. the rod is fixed in the center of a disk. the disk has mass 125 kg and radius 0.2 m. they turn freely about a fixed axis through the center. what is the angular acceleration of the rod, in radians/s?

a. 2
b. 25
c. 50
d. 75
e. 125

The angular acceleration of the rod is 2 rad/s².

(a) is correct option.

Explanation:

Given that,

Mass of string = 5.00 kg

Radius = 0.100 m

Mass of disk = 125 kg

Radius of disk = 0.2 m

We need to calculate the acceleration

Using balance equation

Put the value of m

....(I)

We need to calculate the tension

Using balance equation

Put the value into the formula

....(II)

From equation (I) and (II)

Put the value into the formula

We need to calculate the  angular acceleration of the rod

Using formula of angular acceleration

Put the value into the formula

Hence, The angular acceleration of the rod is 2 rad/s².

electrical potential energy =0.072 j

explanation:

electrical potential energy is given by

u= q δv

q= charge=6 c

δv= potential difference and is given by

δv= e d

e= electric field

d= distance=5 mm=0.005 m

δv=2.4 (0.005)=0.012 v

now electric potential energy= u= q δv

u=6 (0.012)

u=0.072 j

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