Question

2. Three particles each having a mass of 100 g are
placed on the vertices of an equilateral triangle of
side 20 cm. The work done in increasing the side
of this triangle to 40 cm is
(1) 5 x 10-12 J
(2) 2.25 * 10-10 j
(3) 4 x 10-11 J
(4) 6 x 10-15 J​

Answer 1

Answer:

Explanation:

=> Here, It is given that,  Three particles each having a mass of 100 g are placed on the vertices of an equilateral triangle of  side 20 cm.

Thus, M = m = 100 g = 0.1 kg

Ri = 20 cm = 0.2 m

Rf = 40 cm = 0.4 m

G = 6.67 * 10⁻¹¹ Nm² kg⁻²

=> Here, work done is the difference of the Final gravitational potential 'Vf' and Initial gravitational potential 'Vi'.

∴ W = Vf - Vi    [But V = 3(-GmM/R)]

Thus, W = 3[(-GmM/Rf) - (-GmM/Ri)]  { here, R is radius}

W = 3[-GmM(1/Rf - 1/Ri)]

= 3 [-GmM(1/0.4 - 1/0.2)]

= 3 [-GmM( 1 - 2 /0.4)]

= 3 [-GmM(-2.5)]

= 3 * 6.67 * 10⁻¹¹ * 0.1 * 0.1 * 2.5

= 5.0 * 10⁻¹² J

Hence, The work done in increasing the side  of this triangle is 5.0 * 10⁻¹² J.

Answer 2

Explanation:

ans. (1)

hope you understand the ans.