Principles of Dairy Machine Design

Module 2. Dynamics

Lesson 8
SOLVING NUMERICAL

8.1 Problem

1. A trolley weighing 2000 N moves on a level track for a distance of 2 km. The resistance of the track is 5 N per 1000 N weight of trolley find the work done.

Sol: Given,

Resistance force,

Distance, S = 2km = 2000 m

Using the relation

W.D = P X S

= 10 X 2000 = 20,000 N-m

8.2 Problem

A man is drawing, water from a well, with a light bucket which leaks uniformly. The bucket when full weight 20 N and when it arrives at the top, it weight 10 N Find the work done, if depth of the well is 30mt.

Sol:

Initial weight P₁ = 20 N

Final weight P₂ = 10 N

Depth of the well, S = 30 m

Work done = P X S

= 15 x 30 = 450 N-m

8.3 Problem

Calculate the work done in pulling a block weighing 200 N for length of 10m up a smooth inclined plane which makes 30° with the horizontal.

Sol:

Weight of the block = 200 N

Inclination of block = 30°

Distance S = 10 m

Using the relation

Work done = P X S

= 100 x 10 = 1000 N-m