Recent content by confusedaboutphysics

A 20.0 g bullet strikes a 0.600 kg block attached to a fixed horizontal spring whose spring constant is 6.74 103 N/m and sets it into vibration with an amplitude of 21.2 cm. What was the speed of the bullet before impact if the two objects move together after impact? I've been stuck on this...

thanks chi meson...i got part A as -94485 J, but I'm having problems with part B. I'm still confused about how to find the average force exerted on him by the snow to stop him..help please!

A paratrooper pilot fell 370 m after jumping without his parachute opening. He landed in a snowbank, creating a crater 1.0 m deep, but survived with only minor injuries. Assume the pilot's mass was 75 kg and his terminal velocity was 50 m/s. (a) Estimate the work done by the snow in bringing...

thanks guys! i understand b now..but I'm still stuck on c. is this the right equation for part c? Wfr = Ffr (dcos30) = .40(300)(-9.8) (4.6cos30) = 4684.85 J?

A 300 kg piano slides 4.6 m down a 30° incline and is kept from accelerating by a man who is pushing back on it parallel to the incline. The effective coefficient of kinetic friction is 0.40. (a) Calculate the force exerted by the man. i got F = mu(k)mgcos(angle) + mgsin(angle) = 0 so F =...

so are my two unknowns Ffr and a?

A 1300 kg car rounds a curve of radius 70 m banked at an angle of 12°. If the car is traveling at 88 km/h, how much friction force is required? ok so this is what i did so far but i got stuck. the sum of Fy = mg - Fncos(angle) + Ffrsin(angle) = ma = 0 the sum of Fx = Fnsin(angle) +...

thanks tom and cscott! i understand it much better now

so i know I'm trying to find the acceleration..so would i plug in the answer i got for the mass? Fnet = 749.7 = ma Fnet = 749.7a?? but how can i solve from here if i don't know the Fnet and I'm looking for a?

can someone tell me if I'm doing this right for part A? Fnet = 102(9.8) - (.25)(102)(9.8) Fnet = 999.6 - 249.9 Fnet = 749.7 = ma so if I'm doing this right..where do i go from here?

(a) What is the acceleration of two falling sky divers (mass 102.0 kg including parachute) when the upward force of air resistance is equal to one-fourth of their weight? ________ m/s2 (downward) (b) After popping open the parachute, the divers descend leisurely to the ground at constant...

A person stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.67 of the person's regular weight. Calculate the acceleration of the elevator. how do i start this problem? help please!

thanks cscott! its correct!

webassign is a homework program on the internet...it tells you right away if you're wrong or right...but doesn't give you the right answer until after its due or if you get the answer right.

sorry...i don't have the answer either..it's due tomorrow night..hmmm...i wander why it won't work...