Machine Design
The contact ratio is the ratio of

Length of arc of recess to the circular pitch
Length of arc of approach to the circular pitch
Length of arc of contact to the circular pitch
Length of path of contact to the circular pitch

ANSWER DOWNLOAD EXAMIANS APP

Machine Design
In replacing the V-belts, a complete set of new belts is used instead of replacing a single damaged belt because

The new belt will carry more than its share and result in short life
New and old belts will cause vibrations
Belts are available in sets
Only one belt cannot be fitted with other used belts

ANSWER DOWNLOAD EXAMIANS APP