Air resistance Definition and 416 Threads

Hello, Why are helicopter blades put on top of the aircraft? Doesnt the air pushed down from the blades push down on the helicopter? Wouldnt it make more sense to have the blades on the bottom?

Calculating effects of air resistance on a ball of mass 0.67kg, being dropped from a height of 4.93m. I have worked out theoretically what time it would take without air resistance using s=ut + 0.5at(squared) however i cannot find an equation that will factor in air resistance. thanks

How do you add air resistance to these 2 equations? #1 sqrt(2 * d / g) = time until impact #2 sqrt(2 * d * g) = velocity on impact The equation for air resistance is: Fd = 0.5 * Air Density * Velocity ^2 * Frontal Area * Drag Coefficient How would you combine this equation with the above...

I'm trying to calculate the torque i would need to pedal when in the highest gear on my bike to sustain a constant speed on level ground. Basically i just want someone to review my calculations and make sure they're correct. I leg press 270 pounds and therefore each of my legs can supply 135...

I'm having a little trouble calculating the force of air resistance for a bicycle. The formula I used is: Fd=1/2pv^2ACd . p= 1.3kg/m^3 v= 13.44 meters/sec. A= 1.15 meters^2 Cd= 0.9 I got an answer, but I don't know if it is correct, can someone please verify?I got 121.52 Newtons.

Having this discussion on another board, basically stemmed from one member saying that a bullet would be in flight for "over 5 seconds"in response to something else someone said about a 0.50 caliber sniper rifle firing at a target 2 miles away. I figured that negating air resistance, the time...

Homework Statement A table tennis ball of mass 10 g is falling towards the ground with a constant speed of 8.2 m/s. Calculate the magnitude and direction of the air resistance force acting on the ball. Homework Equations Not quite sure The Attempt at a Solution m= 10 g which...

Hi Im trying to make an equation for a projectiles path, but this is only over a very short distance, so the projectiles curve aren't taken into account. I am including the air resistance. This is what i have done: m*dv/dt=-k*v2 Differential: dv/v2=-k*dt integrated: -1/v=-k*t+C when: t=0 og...

I understand that in the absence of air resistance, if a ball is thrown vertically upward with a certain initial speed, on returning to its original level it will have the same speed. But when air resistance is a factor, will the ball be moving faster, the same or more slowly than its...

Homework Statement A baseball is hit high into the upper bleachers of left field. After the ball lands in the bleachers, what is the work done by gravity and the work done by air resistance? Wouldn't they both be zero because they are acting 90 degrees to the path of displacement?

Homework Statement Early test flights for the space shuttle used as a glider (mass of 980kg). After a horizontal launch at 480 km/h at a height of 3500m, the glider eventually landed at a speed of 210 km/h. What would its landing speed have been in the absence of air resistance? also, what was...

Homework Statement You drop a single coffee filter of mass 1.4 grams from a very tall building, and it takes 47 seconds to reach the ground. In a small fraction of that time the coffee filter reached terminal speed. a) What was the upward force of the air resistance while the coffee filter...

E.g. A football of mass 1kg is thrown with a speed of 10m/s at an angle of 30 degrees from a horizontal plane. Take air resistance (in Newtons) as 1/15 th of the speed of the ball in the exact opposite direction that the ball is traveling. How long is the ball in the air? and how far...

Homework Statement An object of mass 10kg is projected upwards (from ground level) with initial velocity 60m/s. It hits the ground 8.4 seconds later. Find the drag coefficient, k. Homework Equations dv/dt + rv = -g, where r = k/m The Attempt at a Solution I have used the...

A bicyclist rides 6.2 km due east, while the resistive force from the air has a magnitude of 2.7 N and points due west. The rider then turns around and rides 5.5 km due west. The resistive force from the air on the return trip has a magnitude of 2.2 N and point due east. Find the work done by...

Hi, I have an object that's rotating in the air with constant speed. Now a bit simplified it could be looked as an uniform cylinder that's rotating round and round (not like a propeller). How would air resistance affect this rotation and how could you describe this force with a formula? Thanks

Homework Statement A particle is projected vertically upward with a speed v0 under the influence of a drag force that is proportional to the particle's speed. As the particle falls back down, its terminal speed is vt. (a) Find the time it takes to reach ymax (b) Find ymax (c)Show that...

I have a quick question... when you launch a projectile with no air resistance, the optimal launching angle is 45 degress with no air resistance, but when you add air resistance into the equation, the optimal launching angle for distance changes. Does air resistance make this angle bigger or...

an object thrown vertically upwards into the air takes shorter time to reach its peak height than it does to return to the height of the throw, is this true, how can it be, on the way up it has both the airs resistance ang gravity working against it whereas on the way down only the resistance...

Does the speed of light slow down due to air resistance? I often hear about how the speed of light is constant in a vacuum, and I'm assuming it has something to due with it being different in air due to air resistance. If so, why is this? Since light has no mass, shouldn't air not have an affect...

Homework Statement Hey, As an end of the year easy grade, our physics teacher assigned us a 20 point project in where we design a lab and analyze the data in a power point. I chose to use an inclined plane and a roller cart. My idea was to analyze the effect of a sail (thus creating air...

hi. Suppose that a projectile of mass "m" is launched, from ground level in a horizontal plain, making an angle teta to the horizontal .(with air resistance).now in which angle "m" has the maximum range? .(our teacher said that we should find 53 degrees for teta).please prove it. (first of all...

Homework Statement a particle P of mass m is projected vertically upwards with velocity U_0\mathbf{k} in a uniform gravitational field -g\mathbf{k} with air resistance proportional to the square of the velocity. This is a five part question for which I have found the solutions but there is one...

[SOLVED] Average force of air resistance In early test flights for the space shuttle using a "glider" (mass of 1500kg including pilot), it was noted that after a horizontal launch at 750km/h at a height of 4500m, the glider eventually landed at a speed of 300km/h. What would it's landing speed...

hey guys, I've been experimenting with a pendulum and while doing the error discussion for my experiments i got stuck with the air resistance involved... I've used the formula to find the force applied by the air resistance to the pendulum and ended up with F=2,76*10^-5 *v^2 . (v= velocity of...

[SOLVED] Air resistance Homework Statement A bullet of mass m, diameter d, and muzzle velocity v0 is fired vertically upward from the ground. Assume that the drag can be expressed with Prandtl's air resistance forumla and that the drag coefficient, c, and air density, p, are constant. Find...

Homework Statement Two mass m1 and m2, connected by a massless spring of force constant k, are at rest in equilibrium on a smooth horizontal table. A velocity of magnitude v and direction away from m2 is imparted to m1. a.) Find the speed of the center of mass. b.) Determine the speed of m2...

Hey guys, when an object is free falling, is it still under the effects of air resistance? If it was not under the effects (an environment without air resistance) is free fall possible? (I am looking for an argument that it is under the effects of free fall but all replies will be taken into...

Homework Statement OK I hope someone will help me with this For a projectile with a linear air resistance force Fs =−mkv, show that the maximum horizontal range is given by the equation (v0 + g/k)(x/u0) + (g/k^2)ln(1 - kx/u0) = 0 where u0 = V costheta, v0 = V sintheta are the...

[SOLVED] ODE problem Homework Statement A situation in which the air resistance is proportional to the velocity of an object squared. Object dropped off of a building with height 100m. F = -mg + Fr Fr=.5*cw*p*A*v^2 cw=.5 p = air density = 1? Homework Equations I need to...

I have made a program in Matlab to plot the path of a projectile with air resistance, however, I am lost as to how to obtain an equation for the range. I have found my displacements in the x and y direction by solving second order differential equations, it would be far too difficult to set the...

Hey, I have a question about how to calculate the air resistance, and eventually how much more energy is required to get the same result, once air resistance has been factored in. I have thought of two ways to solve the problem: One way requires multi-variable calculus, which I havn't had...

Could someone tell me if my approch to this is correct? I am given the change in vertical v final(zero), v initial, mass, and frictional coefficient. The question askes for distance. I set up the equation vf^2=vi^2+2ad(mg(frictional coefficent))

Homework Statement A ball of mass "m" is thrown vertically upward with a velocity of "vi." It experiences a force of air resistance given by F=-kv, where "k" is a positive constant. The positive direction for all vector quantities is upward. Does it take longer for the ball to rise to its...

A 0.25 kg pine cone falls from a branch 20 m above the ground. A) With what speed would it hit the ground if air resistance could be ignored? m= 0.25 kg g= 9.8 m/s^2 d= 20 m Ep= (0.25kg)(9.8m/s^2)(20m) = 49 J Ek= 1/2mv^2 49J = 1/2(0.25kg)(v^2) 2(49 J = (0.5kg)(0.5 v^2)) 98 J =...

Homework Statement A 2.76 x 10^-5 kg raindrop falls vertically at constant speed under the influence of gravity and air resistance. After the drop has fallen 131m, what is the work done by gravity? After J is found for gravity, what is the work done by air resistance in units of J. Homework...

I can't seem to come up with a decent formula/accepted value for air resistance. I realize there are things that need to be taken into account, but I am already delving into things way beyond what I've done per the course work, and I don't want to bite off more than I can chew. I understand...

Homework Statement What is the threshold or percent accuracy (100% like plus-minus 10%) of a freefall with air resistance? Homework Equations % accuracy = (actual_free_fall_time)/(ideal_free_fall_time) Computed Free Fall Time based on 9.8m/s^2 net force towards the ground. Actual...

Homework Statement A baseball is thrown straight up. The drag force is proportional to v^{2}. In terms of g, what is the ball's acceleration when its speed is half its terminal speed and a) it is moving up? b) it is moving back down? Homework Equations \sum F=ma mg + bv^{2}=ma - When...

I need to find the velocity with the following information. V=Vo+AT and A=G-KV so how would i find what V equals from this: V=Vo+(G-KV)T

1. In a shotput event, a 2kg shotput is launched from a height of 1.5m with an initial velocity of 8m/s at an angle 60degrees to the horizontal. The formula R=0.0000378.v^2 gives the force due to air resistance (R) where v is the instantaneous velocity. Find the ratio of the gravitational force...

When a baseball flies through the air, the ratio f_{quad} / f _{lin} of the quadratic to the linear drag force is given by \frac{f_{quad}}{f_{lin}} = \frac{cv^{2}}{bv} = \frac{\gamma D}{\beta} v = (1.6 x 10^{3} \frac{s}{m^{2}}) Dv. Given that a baseball has a diamater of 7 cm, find the...

Homework Statement 1. A person throws three identical rocks off a cliff of height h with exactly the same speed v0 each time. Rock A is thrown vertically upward, rock B is thrown straight out horizontally, and rock C is thrown straight downward. If we ignore the effects of air resistance...

I'm trying to figure out this problem... A rock of mass 49 kg accidentally breaks loose from the edge of a cliff and falls straight down. The magnitude of the air resistance that opposes its downward motion is 249 N. What is the magnitude of the acceleration of the rock? I know that I...

Homework Statement I am working on making a small wind tunnel using a 20" fan. What i want to figure out is the force generated by the movement of air. I want to make the size of the tunnel shrink to help induce more velocity in the air (see picture). Homework Equations Bernoulli's...

hi i can't work out how to find air resistance:confused: i am designing/making a paintball sniper rifle. I have worked out the potential fps and need to work out air resistance. Thanks:rolleyes:

If we model the air resistance on a falling person as being proportional to the square of that person's speed, in certain circumstances the proportionality constant between the air resistance and the square of the speed is equal to 0.100 kg/m. Part A What would be the terminal velocity of a...

Homework Statement If a bicyclist of mass 68.0 kg (including the bicycle) can coast down a 6.90 degree hill at a steady speed of 5.80 km/hr because of air resistance, how much force must be applied to climb the hill at the same speed (and the same air resistance)? Homework Equations The...

A 5kg rock falls with an acceleration of 7m/s2. What is the magnitude of the force of air resistance acting on the rock at this instant?

Homework Statement I'm having troubles figuring out what affects the swing of a pendulum. Hypotheses: 1) The period is dependent on the amplitude 2) The period is dependent on the mass of the bob 3) Air resistance and friction will affect the period 4) The period is dependent on the...