Two lenses with focal lengths 10cm and 20cm and made of same material are placed coaxially separated by distance d. The value of d such that the system is achromatic is
A) 20 om
) 30cm
C) 10 cm
D) 15 cm

Brutus, the dog, is pulling a bone to the left with a force of 20 n. lassie, another dog, is pulling a bone to the right with a force of 18n. what is the net force? a. b. c.

Asolid round steel rod 6.25 mm in diameter and 375 mm long is rigidly bonded to the end of solid square brass rod 25 mm on a side and 300 mm long. the geometric axes of the bare are along the same line. an axial tensile force of 5.4 kn is applied at the extreme ends of the assembly. for steel e = 200 gpa and for brass e = 90 gpa. determine the total elongation for the assembly.

Which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?