Recent content by joe215

Homework Statement If a projectile of mass m leaves the carrell of a cannon with a speed v, at what speed will a projectile of mass 2m leave the barrel. I think i need to use conservation of energy but I am not sure how! Thanks

Homework Statement What is 80dB+75dB? I found the individual intesities to be 0.0001 and .0000316228 Then I added them and: dB=10log(1.31622x10^-4/1x10^-12)=81.19 dB Is that right? Thanks!

Homework Statement If volume increases, but pressure decreases, is head added or removed (to a system)? Homework Equations I think that process would be adiabatic, in which case change in heat would be 0, but I am not sure.

Homework Statement A heat engine operates in a Carnot cycle between 80 degrees C and 350 degrees C. It absorbs 21,000 J of energy per cycle from the hot reservoir. a. THe duration of each cycle is 1s. What is the mechanical power output of the engine? b. How much energy does it expel in each...

Homework Statement x=degrees, not radians 0=[(g)(r)(sinX)-(g)(r)(y)(cosX)] / (cosx)-y(sinx) how do I solve for y? Homework Equations The Attempt at a Solution

Homework Statement A person with a weight of 500N stands in an elevator on a scale. from 0-5s his weight reads 500N. from 5-10s his weight reads 700N. from 10-15s his weight reads 500N. from 15-20s his weight reads 300N. Find his acceleration (in each time interval) and his velocity...

A 20 kg monkey holds on to a rope that passes over a frictionless pulley and is attached to a 20 kg bunch of bananas. The monkey starts to climb the rope to get the bananas. a. as the money climbs, do the bananas move up, down, or remain at rest? b. as the money climbs does the distance...

There is an upwards normal force on the person and a downwards force of mg on the person. Also, I think the acceleration of the elevator=acceleration of the person. Also, upwards is the positive direction. Since the scale reads 700N, then the net forces on the person equal 700N...

Homework Statement A person has a normal weight of 500N. The same person is standing on a scale in an elevator and the scale reads 700. what is the acceleration of the elevator? The Attempt at a Solution How do I apply the formula Fnet=ma to this problem?

If I used 13km/h instead of 12km/h, would the answer be right?

1. Homework Statement A hunter wishes to cross a river that is 1.5 km wide and flows with a speed of 5.0km/h parallel to its banks. the hunter uses a small powerboat that moves at a maximum speed of 12 km/h with respect to the water. What is the minimum time necessary for crossing? 3...

Ok is this right... First I figure out how long it takes the fugitive to attain a velocity of 8m/s and the distance he travels in that interval. So... t=(V-Vo)/a 8/4= 2s In 2s he reaches 8m/s. d=VoT + 1/2at^2 d=1/2(4)(2^2) d=8m Now, when the distance of the train and fugitive are equal...

I don't see the error?

Homework Statement A fugitive tries to hop on a freight train traveling at a constant speed of 6.0m/s. The fugitive starts from rest and accelerates at 4.0m/s^2 to his maximum speed of 8.0 m/s. How long does it take him to catch the train? What is the distance traveled to catch the train...

Homework Statement A falling stone takes 0.28s to travel past a window 2.2m tall. From what height above the top of the window did the stone fall? The Attempt at a Solution Vo=?, the velocity at the top of the window a= -9.8m/s^2 t=.28s d=2.2m v=? Vo=(1/2at^2-d)/-t...