If friction did not exist, could you stop a bicycle that you were riding?
Run into a wall? Roll up a hill? Attach a generator to the spinning tire, and attach a resistive load? (Requires rolling friction between road & tire) Grab on to passing objects, and push in the opposite direction? Use a bottle rocket? (Newton: for each action...) Use an anchor? Or, wait for it to rain, then collect the rain drops in a container. You will impart momentum into the rain drops, and once they are going your speed, you can dump them(and collect more). Eventually all of your momentum will be imparted to the dumped water, and you will (effectively) stop. Just a few ways.
What is the bicycle's speed at the bottom of the hill?
The force that causes the bike to accelerate is the component of its weight that is parallel to the hill. Force parallel = m * g * sin θ sin θ = height/length = 104/364 Force parallel = 96 * 9.8 * 104/364 = 268.8 N To determine net force on the bike, subtract the friction force. Net force = 268.8 – 250 = 18.8 N To determine the acceleration, divide by 96 kg. a = 18.8 ÷ 96 This is approximately 0.1958 m/s^2. To determine the final velocity, use the following equation. vf^2 = vi^2 + 2 * a * d, vi = 9, d = 364 vf^2 = 9^2 + 2 * (18.8 ÷ 96) * 364 = 13767.4 ÷ 96 vf = √(13767.4 ÷ 96) This is approximately 11.9754 m/s. (12 m/s)
When riding a bike up a slope, at some point it takes less energy to get off and walk the bike. How do you calculate the angle when walking is better?
There are many answers saying bikes are always more efficient given the right gear. This is not entirely true. The transition point will depend on your power to weight, and your bike weight fraction.At higher speed, walking power is dominated by inertial losses. Optimal walking speed for normal people is about 1.6 m/s. Cycling is good at high speed because it allows the person to go faster without moving his legs excessively fast. Below walking speed though, there are not many advantages. The criterion we will use is where climbing speed at threshold power falls below walking speed.Transition Grade = (Power:Weight)/(Bike weight fraction)/(g)/(walking speed)Here are some data points:The best professional cyclists can output a sustained (for one hour) power of 6W/kg. An average commuting cyclist will be closer to 2W/kg.A light (UCI limit) road bike will weight about 6.8 kg. If you are a heavy rider of 100 kg, then this is about 7% of your weight. A normal commuting bike might weigh about 12 kg, and an average cyclist might weigh 80 kg, giving a fraction of 15% body weight. A heavy touring bike with some cargo might weigh 30 kg, and a light cyclist (such as Contador) might weigh 60 kg, for 50% rider weight.a light, weak cyclist riding a heavy loaded bike as given above will reach walking speed at 8.5%, above which he will ascend the hill about 50% faster without a bike.A heavy, very strong cyclist riding a very light bike will reach walking speed at about 36% grade. Above this he will ascend the hill about 7% faster without a bike.A normal commuter in this example will reach walking speed at about 11% slope.Experientially, these numbers seem about right.This is an upper bound and in both cases it’s likely other factors would make walking preferable earlier (gearing, pedaling inertia, handling, CG, etc.)
How serious is dumping the clutch?new 2 stick shift.?
Im still in high school and im learning the stick shift and i was wondering how much damage i could do to the tranny if i ran high rpms and suddenly dumped the clutch, i havent done it so far, i revved but i didnt dare to dump the clutch. I'm also having trouble "feathering", I keep popping the clutch and the engine stops and i know its been only 2 days since i started with the stick shift but i want to get it right. What happens if i dont want to gradually accelerate when i release the clutch... I mean i can release the clutch slowly and the car will still move forward and then i can use the accelerator pedal.... so this way i dont have to worry about the engine stopping due to bad clutch release... but i know this has its own cons? and in the long run this isnt right?
Friction! yes or no? Physics?
The speed found in part (a)( which is 20.7m/s) is the same as if the woman fell vertically through a distance of 21.9 m. The result of part (b)(which is −3.16 10^3 J) is negative because the system loses mechanical energy. Friction transforms part of the mechanical energy into thermal energy and mechanical waves, absorbed partly by the system and partly by the environment. If the slide were not frictionless, would the shape of the slide affect the final answer? Can you please explain why
What is the energy conversion taking place when a car goes uphill?
If the car is going uphill then it’s fighting gravity pulling it back down again at 9.8m/s/s and so it needs an acceleration greater than that. It’s doing it by means of a chemical explosion in the engine if it’s diesel or petrol, or by means of drawing a current from a battery if it’s electric. In either case we are turning chemical potential into linear kinetic. Without knowing velocities we can’t calculate the magnitudes but by the looks of your question we don’t need to which is always good news as far as I’m concerned - the less the maths we have to do the better.Once the car’s at the top of the hill, it gains a potential if it rolls down the other side. The approved method in driving is not to coast but control your speed with the motor but something I used to like doing (especially on a motorbike) was disengaging the clutch and letting it go. In this case I was turning potential into kinetic. There’s no violation of laws here (well, there might have been a violation of traffic laws down those hills as I got some pretty nice speeds up) because the energy expended in getting the vehicle up the hill was always greater (some got wasted as heat) than the potential-to-kinetic getting down again.