A system consisting of two masses connected by a massless rod lies along the x axis. If 0.2 kg mass is at a distance x = 0.5m while a 0.3 kg mass is at a distance x = 1m, then the x - co-ordinate of the centre of mass will be at ______________.

(a)

2.5m

(b)

5m

(c)

22.5m

(d)

0.8m

If earth suddenly contracts to 0.75 times of its present radius, then the length of the day becomes _______________

(a)

12 hr

(b)

18 hr

(c)

15.5 hr

(d)

13.5 hr

The angular momentum of a rotating body is doubled, its K.E. of rotation becomes ________________

(a)

Two times

(b)

Four times

(c)

Halved

(d)

Eight times

Where will be the centre of mass on combining two masses m and M (M > m)?

(a)

Towards m

(b)

Towards M

(c)

Between m & M

(d)

away from m & M

Two bodies of masses 2 kg and 3 kg have position vectors \(\hat { i } +2 \hat { j} +\hat { k} \) and \(\hat { -4i } - \hat {(-3j)} +\hat { 6k} \) respectively. The centre of mass of this system has a position vector _____________.

(a)

\(\hat {- 3i } -\hat { j}\)

(b)

\(\hat {5 i } - \hat { j} +2\hat { k} \)

(c)

\(\hat {-2 i } - \hat { j} +4\hat { k} \)

(d)

\(\hat { -3i } - \hat { j} +\hat7 { k} \)