In mountainous regions, road builders construct runaway truck ramps near the bottoms of long hills. These ramps allow a truck with failed (not working) brakes to leave the main road and coast uphill to a stop on sand or gravel-filled paths. Explain why the sand or gravel helps stop the truck. (Hint: Think about running on a very sandy beach.)
2006-11-28 09:05:31 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Earth Sciences & Geology
First runaway truck ramps are angled up hill using the force of gravity to slow the truck down. Then sand or gravel is used because they are soft loosely packed material.
What happens is the truck's tires start digging into the sand or gravel when it hits the runaway ramp. The deeper the tires dig into (bog down) the sand or gravel the more resistance the sand or gravel offers to the trucks forward motion. In the form of coefficient of fraction. The deeper the tires dig into the sand or gravel the higher the coefficient of fraction. which, which combined with the force of gravity causes the truck to slow down gradually without wrecking.
If the truck is going fast enough it will bog down into the sand or gravel so deep that the truck is bottoming out on the sand or gravel further increasing the coefficient of fraction.
Bottoming out is a common term used with a vehicle has buried up in mud, sand, or gravel so deep that the underside of the vehicle is dragging the ground.
2006-11-28 09:21:50 · answer #1 · answered by JUAN FRAN$$$ 7 · 0⤊ 0⤋
The sand or gravel allows the wheels to sink into the soft roadway. This sinking increases the surface area contact between the road and the tires thus increasing the friction. The more friction the easier it is to stop.
The hint gives you a clue as well. In addition the road moves away from the wheel causing it to slip and spin in place more than on the other road.
So in a sense it also decreases the friction on the bottom of the tires while increasing the friction on the sides. This allows the vehicle to "lose traction" and be propelled more slowly assisting gravity with the decelleration.
2006-11-28 09:19:12 · answer #2 · answered by epaphras_faith 4 · 0⤊ 0⤋
The sand and or gravel will produce more resistance against the truck's momentum, especially as the wheels start bogging down in the soft material. It will bring the truck to a rest far quicker than a hard-packed flat surface, such as a paved road.
2006-11-28 09:11:42 · answer #3 · answered by Anonymous · 1⤊ 0⤋
the sand and gravel are very soft and fluffy. It is also about 5 feet deep. the truck turns into a bulldozer. The weight of the truckcannot push that much material uphill.
Trucks that slam into those run-away barriers make one hell of a mess.
2006-11-28 18:33:43 · answer #4 · answered by mig_killing_pigs 2 · 0⤊ 0⤋
Because sand has less friction
2006-11-28 09:10:01 · answer #5 · answered by a2k929 1 · 0⤊ 1⤋
annabelle! did i not already give you the answer?! the sand creates friction!
2006-11-28 10:35:41 · answer #6 · answered by Kelly P 4 · 0⤊ 0⤋