mechanical · 26 minutes · Official OETT Aligned
Friction & Ramps
Grip, sliding, and how steepness affects pulling
What to know
- friction: resistance to sliding
- grip or traction
- lubrication: reducing rubbing
- ramp length and steepness
Friction can help tires grip or make a load harder to slide. A ramp changes how much force you need.
The core rule
A longer ramp to the same height needs less force without friction, but the load travels farther.
Friction acts against sliding between surfaces. It often takes more force to start a load moving than to keep it sliding. Oil can reduce friction between metal parts. A shallower ramp reduces the force needed to raise a load, but real ramps also have friction to overcome.
Worked examples
Example 1: easy
Rough dry concrete resists sliding more than oiled steel.
- Compare the same object sliding on rough dry concrete and oiled steel.
- The rough dry surface provides more resistance to sliding in this example.
The surface can change friction even when the load stays the same.
Example 2: medium
A longer ramp to the same height needs less ideal force.
- Both ramps lift the same load to the same height. Ignore friction.
- The longer ramp needs less force because the load travels farther.
The same lifting work is spread over a longer distance.
Example 3: hard
When friction increases on a ramp, input force rises even though the height and load stay fixed.
- Keep the ramp and load the same, but increase friction.
- You need more uphill pull to overcome the extra downhill resistance.
Friction adds to the force needed for lifting.
Common mistakes
Friction is always a problem.
Friction makes sliding harder, but it also gives shoes and tires the grip they need.
Put it into practice
Use guided explanations, check your answers, and try a new variation.