Question

A massless rigid rod is in equilibrium as shown in figure. Find the normal reaction at knife -edge 1

Answer 1

Answer:

Let the initial velocity of the body be u m/s; and the constsnt acceleration be a m/s². Then displacemet (distance covered) of the body after t second is given by

s = u t + ½ a t²

The body covers 20 m in 2s and 80 m in 4 s.

20 = u×2 + ½ a 2²; => 20 = 2 u + 2 a

u + a = 10

80 = u×4 + ½ a 4²; => 80 = 4 u + 8 a; this gives,

u + 2 a =

Solving (2) and (3) for u and a we get

u = 0 m/s and a = 10 m/s²

To obtain the distance covered in the next 4s we need to find the velocity at the beginning of this interval using,

v = u + a t =>

A uniform metre scale has two weights of 10 gf and 8 gf suspended at the 10 cm and 80 cm marks respectively. If the metre scale itself weights 50 gf, find where must the weight be, so that

At the balancing condition, Anticlock wise moment must be equal to clock wise moment.

Clockwise moment, about the balancing point is

= moment by 80 gf

=80gf×(80−X)cm

=6400gfcm−80Xgfcm.....(1)

Anticlock wise moment about the balancing point is

= moment by 10 gf + moment by 50 gf

=10gf×(X−10)+50gf×(X−50)

=10Xgfc,−100gfcm+50Xgfcm−2500gfcm.....(2)

At the balancing