At the tip of either of the magnets poles
Answer:
0.2932 rad/s
Explanation:
r = Radius = 2 m
= Initial angular momentum = 
= Initial angular velocity = 14 rev/min
= Final angular momentum
= Final angular velocity
Here the angular momentum of the system is conserved

The final angular velocity is 0.2932 rad/s
Answer:
5 ohms
Explanation:
Given:
EMF of the ideal battery (E) = 60 V
Voltage across the terminals of the battery (V) = 40 V
Current across the terminals (I) = 4 A
Let the internal resistance be 'r'.
Now, we know that, the voltage drop in the battery is given as:
Therefore, the voltage across the terminals of the battery is given as:

Now, rewriting in terms of 'r', we get:

Plug in the given values and solve for 'r'. This gives,

Therefore, the internal resistance of the battery is 5 ohms.
Answer:
The critical stress required for the propagation of an initial crack
= 21.84 M pa
Explanation:
Given data
Modulus of elasticity E = 225 ×

Specific surface energy for magnesium oxide is
= 1 
Crack length (a) = 0.3 mm = 0.0003 m
Critical stress is given by
=
-------- (1)
⇒ 2 E
= 2 × 225 ×
× 1 = 450 ×
⇒
a = 3.14 × 0.0003 = 0.000942
⇒ Put these values in equation 1 we get
⇒
=
⇒
= 4.77 × 
⇒
= 2.184 ×

⇒
= 21.84 
⇒
= 21.84 M pa
This is the critical stress required for the propagation of an initial crack.