Question

The ball bearings used in a machine are of different materials, This is because

• A. adhesive forces are greater than cohesive forces.
• B. adhesive forces and cohesive forces are equal in magnitude , opposite in direction.
• C. adhesive forces are less than cohesive forces.
• D. machine looks good, attractive.

Answer 1

The correct option is B adhesive forces and cohesive forces are equal in magnitude , opposite in direction.

Solution The ball bearings are of different

Materials due to lubrication which

in tarn prevents sliding friction.

Microscopically, friction is when

the adhesive forces are greater

then cohesive forces. If sliding

friction is zero, both forces are

equal in magnitude but opposite

in direction

Option - B is correct.