increasing temp

If a house has insulated walls.It contains a volume of 100m3 of air at 300K.What is the energy required to increase the temperature of this diatomic gas by 2C. how do I get the ans I used the equation C=7R/2?

MAGNITUDE

If A=(12i-16j) and B=(-24i+10j),what is the magnitude of vector C=(2A-B)? I have been tried: A=(12-24)=-12i X2=24 B=(-24+10)=-6j =-6 R^2=24^2+6^2=24.7

kINETIC Friction

A 9Kg hanging weight is connected to a string over a pulley to a 5Kg block that is sliding on a flat table.If the coefficient of kinetic friction is .15,find the tension in the string. I belive the equasion is :T=M1M2(SIN0+1)/M1 +M2 Kinetic friction is F-fK= How does is problem work? My text book asks the question,give t ...continues

Force

A 50 kg ice skater is moving at 5m/s when she grabs the loose end of the rope,the opposite end of which is tied to a pole.She then moves in a circle of radius 1M around the pole.What is the force exerted by the rope on her arms? I think F=M*V^2/r =250N am I right?

steam to water

Steam at 100C is added to ice at 0C.The mass of the steam is 10g.The mass of ice is 50g.What is the final temp of the mixture? I know the conversion of steam to water is Ms(2.26x10^6J/kg) How does this problem work?

resultant force

The speed of a 4Kg object is given by v=(2t)m/s,where t is in seconds.At what rate is the resultant force on this object doing work at t=1 second? I think Force =8N W=FCHANGEr =16W AM i RIGHT?

change in potential energy

A 10Kg object is initially at the top of a rise,at point A.It then moves down to point B.Choose point B to be the zero level for gravitational potential energy.Find the change in potential energy of the object if point B is 10 M lower than point A? (10Kg)(9.8m/s)(10m)=-980 am I right?

angular acceleration

At t=0,a wheel rotating about a fixed axis at a constant angular acceleration has anangular velocity of 2 rad/s.Two seconds later it has turned 5 complete revolutions.What is the angular acceleration of this wheel? I think- (2rad/s)(2s)+1/2(3.5rad/s^2)(2s)^2=14rad Am I right?

angular momentum

A car of mass 100Kg moves with a speed of 50m/s on a circular track of 100m.What is the magnitude of it's angular momentum relative to the center of the racetrack? I say- L=mv rsin l=(1000Kg)(50m/s)(100m)SIN90=4.5X10^6 Why am I wrong? my ans is in Kg M^2/S

sine wave problem

If a sinusoidal wave is described by y=(.30m)SIN(.20X-40t) I am clueless on this problem, do I solve for x? x=.30SIN-40t/.20t?Help