physics student

The forces acting on the arm of a person lifting a dumbbell. The force F is the force pulling on the hand due to the weight of the dumbbell, the force Warm is the weight of the arm and T is the tension due to the muscles connecting the arm and the trunk....

a 715 N person walks up three flights of stairs, covering a total vertical distance of 10.5 m. (a) If, as is typical, only 20% of the caloric (food) energy is converted to work by the muscles, how many joules and food calories of energy did the person use...

Which of the following statements about emission spectra is correct? All the lines are evenly spaced. All noble gases have the same spectra. Each line corresponds to a series of wavelengths. All the lines result from discrete energy differences

my values were θ = 40o, m1 = 397g, m2 = 314g, |Fext| = 4.7 N... i got my answer as 0.971 N

Thanks, I am unsure of how to start the problem though.