Suppose you have two forces pand p. How would you combine them in order to have resultant force of magnitudes (a)zero (b) `2_barF and barF`?

How would you combine two lens of focal length 25cm to 2.5 cm to make a telescope?

The minimum number of unequal forces that can have zero resultant is

Two equal forces have their resultant equal to either. What is the inclination between them?

A galvanometer having a coil resistance 120 Omega shows full scale deflection for a current of 2.5 mA. How would you convert it into an ammeter of range 0 to 75A?

Samples of four metals A,B,C and D were taken and added to the following solutions one by one.The results obtained have been tabulated as follows. Use the table above to answer the following questions about metals A,B,C and D. (i)Which is the most reactive metal? (ii)What would you observe if B is added to a solution of copper (II) sulpahate? (iii)Arrange the metals A,B,C and D in the order of decreasing reactivity.