Recent content by starhallie

Thank you so much for your help! :approve:

I=P/V =60W/(120V-25V) =0.63 A R=V/I =95V/0.63A =151 ohms?

I guess I just don't understand what voltage to use and why. :frown:

120v - 25v = 95v?

Homework Statement A 60W lamp is placed in series with a resistor and a 120V source. If the voltage across the lamp is 25V, what is the resitance R of the resistor? Homework Equations I derived R= V2/P from ohm's law to solve this problem. The Attempt at a Solution R= V2/P...

PE = mgh = (900kg)(9.8 m/s2)(200m) PE = 1,764,000 kgm2/s2 I think? :rolleyes:

c) 10 m/s f) KE= 1/2(900kg)(20 m/s)2 KE= 100,000 kgm2/s2 g) vcar= 200m/10s = 20 m/s PE= 1/2(900kg)(20 m/s)2 PE= 100,000 kgm2/s2 I hope that's at least a start? :shy:

Homework Statement A 900-kg car is pulled by a constant force of 1800N. Assume friction on the road surface is negligible. a) What is the acceleration of the car? b) If the car starts from rest, what is its speed after 10s? c) What is the average velocity of the car during the 10s? d)...

Thank you for the help. I ended up figuring it out!

Homework Statement Standing in line next to the scariest rollercoaster of all time, you see your friends screaming their heads off as they come speeding out of the end of the ride. The sound of their screams is about 30% higher in pitch than normal due to the Doppler shift caused by their...

Thank you very much for your help!

Thanks for your help :smile: This is what I got so far... PEspring= 1/2kw2= 1/2(180 N/m)(0.05m)= 0.225 J ... but I'm having trouble understanding the rest.

Homework Statement A 2kg object is suspended from a vertical spring that has a constant of 180N/m. a) How far does the spring stretch from the unstrained length? b) If the object is now pulled downward an additional distance of 5cm. What external force was required to do so? c)...

Sorry for the very late reply, pafala... thank you so much for your help on this problem. I truly appreciate it!

Homework Statement A particular object is moving on a horizontal (x,y) plane with a velocity of 10 m/s in the (+x) direction. It is simulaneously acted upon by two horizontal forces. F1= 225 N at an angle of 30 degrees with respect to (+x) and F2= 135N at an angle of -75 degrees with respect...