Earth's magnetic field is almost same to that of the bar magnet. The magnetic field of the earth occurs from its core. It has an inner core which is solid in nature. in the outer core, there is a motion of the liquid due to heat flow from the inner core to the core mantle boundary which proves that the outer core is liquid and moving. The Earth's core consists of iron and nickel as the Eddy currents in the iron and nickel liquid helps generating the Earth's magnetic field.

Hence, all the three statements are true and can be used to explain the Earth's magnetic field.

5 0

4 years ago

Read 2 more answers

In the figure below the pulley is a solid disk of mass M and radius R with rotational inertia MR 2/2. Two blocks one of mass m a

matrenka [14]

Assuming you are looking for the acceleration a:

1. $m_1a = T_1 -m_1g$
2. $m_2a = m_2g - T_2$
where T is the tension and a is the acceleration of the blocks. The acceleration of the two blocks and the acceleration of the pulley must be equal.

The torque on the pulley is given by:
3. $\tau = \overrightarrow r \times \overrightarrow F = (T_2 - T_1)R = I\alpha = \frac{1}{2} MR^2 \frac{a}{R}$
where $I = \frac{1}{2} mR^2$ and $a = \alpha R$ .

Combining the three equations:
$T_2 - T_1 = \frac{1}{2} Ma \\ m_2g - m_2a -m_1g - m_1a = (m_2-m_1)g - (m_1 + m_2)a = \frac{1}2}Ma \\ \\ a = \frac{(m_2 - m_1)g}{m_1 + m_2 + \frac{1}{2}M }$

6 0

3 years ago