🟢 Lazy Man Flashcards – NSSCO Physics (Friction)

What is friction?

Friction is the resistive force that opposes the relative motion between two surfaces in contact.

Which force prevents slipping when walking?

Static friction prevents slipping by gripping the ground until the limit is exceeded.

Which factor most affects the size of friction?

The nature/roughness of the surfaces in contact. Rougher surfaces = more friction.

Does surface area directly affect friction?

No — friction mainly depends on normal force and surface texture, not on surface area.

What type of friction acts on a ball rolling on grass?

Rolling friction, smaller than sliding friction, slows the ball down.

Which force opposes a car moving through air?

Air resistance (a form of fluid friction) opposes motion through air.

Why does a rough road slow down vehicles?

Increased surface irregularities cause larger friction opposing motion.

What is the disadvantage of too much friction in machines?

It causes wear and tear and energy loss as heat.

What is one advantage of friction in daily life?

Provides grip and traction, e.g., walking or car tyres gripping the road.

Which method reduces friction in engines?

Lubrication with oil/grease smoothens contact surfaces.

Why are ball bearings used in bicycles?

They reduce sliding friction to rolling friction, which is smaller.

Why are streamlined shapes used in cars and airplanes?

To reduce air resistance and increase efficiency/speed.

Which friction acts when a box just begins to move?

Static friction at its maximum value.

Why do shoes wear out faster on rough surfaces?

Greater abrasive friction wears away shoe material.

What energy change happens due to friction?

Kinetic energy is converted into heat and sometimes sound.

Why do machines need oiling?

To reduce friction, preventing overheating and increasing efficiency.

Why do brakes stop a bicycle?

Brake pads increase friction with the wheels, converting motion to heat.

Why is friction called a 'necessary evil'?

It is useful for grip and walking but also causes energy loss and wear.

Why do tyres have treads?

To increase friction/grip, especially on wet surfaces, preventing skidding.

Why are skis smooth?

To reduce friction for faster sliding on snow.

Why does friction increase with load?

More normal force pushes surfaces together, increasing contact irregularities.

Why is friction less on smooth surfaces?

Fewer microscopic irregularities, less resistance.

Why are oil tankers streamlined?

To reduce water resistance for efficient movement.

Why are chalkboards rough?

Increased friction allows chalk particles to stick and form marks.

Why do we slip on smooth floors?

Low friction reduces grip between shoes and floor.

What happens to kinetic energy when friction acts?

It is converted mainly into heat.

Why does friction produce heat?

Microscopic irregularities interlock and resist motion, releasing energy as heat.

Why do machines wear out?

Continuous friction causes surface damage and material loss.

Why is oil applied to door hinges?

To reduce squeaky friction, allowing smooth motion.

Why do car engines overheat without oil?

Excess friction converts kinetic energy into heat, damaging parts.