Question

1.d) Which surface produces minimum friction?

2.b) What is LED? Explain it's utility.
d) On what factors fluid friction depend? Mention any 2 points.
g) What is pitch or shrillness of a sound?
j) How does the atmospheric pressure change with increase in temperature?

3.g) A pendulum oscillates 80 times in 5 seconds. Find its time period and frequency
h) Explain the application of electrolysis.

4.a) Show that frictional force depends on the nature of the two surfaces on contact.

*Important questions so please answer judiciously and correctly
*Mention the question no. correctly
*Please don't leave the questions in middle or don't answer the half​

Answer 1

• smooth surfaces
• LED is light emitting diode. it is used for lightning the rooms.
• Pitch is the characteristic which differentiates a sharp or shrill sound from a grave one.
• With increase in temperature atmospheric pressure decreases.
• In 1 second 80/5 times, i e., 16. So, frequency = 16 Hz and time period = 1/16 s
• Electrolysis is helpful in extraction of metals like aluminium from their ores. It is also applicable on carrying out works with high voltage application.
• If the surface is smooth frictional force almost tends to zero. If the surface is rough then frictional force will be present. so it depend on surface in contact. it is a contact force.