dynamo U0001f92f walking on building magic

A 1.5m tall boy is standing at some distance from a 30m tall building.The angle of elevation from his eyes to the top of the building increases from 30 to 60o as he walks towards the building.Find the distance he walked towards the building.

If rotational velocity of a dynamo armature is doubled, then induced e.m.f. will become

Write T against true and F against false in the statements. Lightning conductor cannot protect a building from lightning. (T/F)

If the angular speed of the armature of a dynamo is doubled then the amplitude of the induced e.m.f will become_______.

Show that for virtual object, a convex mirror gives (a) real and erect image of u lt f and (b) virtual and inverted image for u gt f .

The initial velocity of a particle is u (at t = 0) and the acceleration f is given by f = at. Which of the following relation is valid?