Recent content by petuniac

Thanks again!

Thank you Matheyrichs! You've made it much clearer to me! I made an error in quoting the original question.. the elevator mass is 85 kg. Ok, so for the solution I get... Pout = Fv = mgh = (85*9.81*1) = 833.85 W Pin = 10000 W e = Pout/Pin = (833.85)/10000 *100 = 8.33% The only...

thanks!

Sorry Reshma but I am still confused ... if I solve for F using the P = Fv equation what does this accomplish as I need to calculate the efficiency, and why would I use the 10 kW power given for the motor in that equation and the speed of the elevator?? Please help.

Homework Statement Find the equation of a circle that passes through the points A(2,2) and B(5,3) and has its centre on the line y = x +1 Homework Equations (x-h)^2 + (y-k)^2 = r^2 The Attempt at a Solution can get 2 equations knowing the 2 points the circle passes through but...

Homework Statement An 8.5 kg elevator is pulled at a constant velocity of 1.0 m/s by a 10.0 kW motor. Calculate the efficiency of the motor. Homework Equations W = change in E = Fd e = Work out/Work in * 100 = energy out/energy in *100 Epotential = mgh Ekinetic = 1/2mv^2...

Homework Statement If Terry had run 2.0 km/h faster, he would have taken 30 minutes less to cover a 25 km run. What was Terry's running speed? Homework Equations d=vt The Attempt at a Solution equation 1 25 = xy equation 2 25 = (x +2)(y-0.5) ? Is this right...

Homework Statement Fill in the blanks... 1. ___________ indicates how close a measurement comes to its real value 2. the ___________ of a measurement can only be as accurate as the measuring device used. 3. __________ indicates how close a set of measurements are to one another...

thanks for the replies... please see my comments below 1) why does the time not look correct? I re-did the calculation with the same result vf = vi + at 6.8 = 7 + (-0.3)t t = (6.8-7)/-0.3 t = 0.67 s 2) this problem was given as part of linear kinematics... 3) so am I doing this...

thanks for your help!

so vi = 5.05 m/s.. is this right?

a salmon has to jump a 1.3 m falls to complete its journey. How fast must is be going when it leaves the water to reach the water on top of the falls? vi = ? vf = 0 m/s (can i assume this) a = -9.8 m/s^2 d = 1.3 m t = ? use vf^2 = vi^2 + 2ad to find vi 0 = vi^2 + 2(-9.81)(1.3)...

you are playing darts and are wondering how far the dart is dropping on its journey to the target which is 4 m away. The dart leaves your hand at 7 m/s and is accelerating at a rate of -0.3 m/s^2. work so far... find final velocity is x-direction from vf^2 = vi^2 + 2ad vf = 6.8 m/s...

5 cm = 0.05 m which then gives an answer of 860, which is still the wrong answer and i was under the impression that the units did not need to be convered as this was a ratio?

I have a problem that shows a picture with an arrow in it. The arrow in the picture shows that is is 5 cm in length. The actual length of the arrow is given in the problem as 43 m. The question asks for me to determine the scale of the picture. So, I've set up a ratio: 1/x = 5/45 (1 cm...