One method used to determine unknown atomicmasses consists of precisely measuring the kinetic energiesof the particles involved in a nuclear reactionand using known atomic masses. The mass of 34Si isdetermined by the 30Si(18O, 14O)34Si reaction initiatedby 100-MeV 18O particles. The outgoing particles have86.63 MeV of energy, which can be determined onlyby measuring the 14O energy and using the conserva-tion of momentum and energy. (a) What is the Qvalue of the reaction? (b) What is the mass of 34Si assumingthe other three masses involved are known(see Appendix 8)?
Nonconservative Forces Work Done By Nonconservative Forces ● In the presence of non-conservative forces, the total mechanical energy is not conserved: ○ W totalW conservativnonconservative ○ W = − ΔU + W = ΔK total nc ○ W nc ΔK + ΔU = ΔE Examples ● What height H must we release the car if it just makes it around the circular loop of radius R ● A shot put (m = 7.26 kg) is shot at an angle of 43.4 degrees and released from a height of 1.82 m above ground level then it lands with a final velocity of 20m/s. It lands a horizontal distance of 17.7 m from the release point. With what speed does the shot put leave the thrower’s hand ● A block of mass m1 = 2.40 kg is connected to a second block of mass m2 = 1.80 kg. When the blocks are released, they move through a distance d = 0.500 m at which point m2 hits the floor. The coefficient of friction between m1 and the table is 0.450. Find the speed of the blocks just before m2 lands. ● A 20.0 kg child slides down a 1.0m long slide inclined at 40.0o. The child starts at rest on the top and experiences a frictional force of 5.00 N. What is the speed of the child at the bottom of the slide ● An 80 kg jogger starts from rest and runs uphill in a stiff breeze. At the top of the hill the jogger has done a work W = 1.8 x 104 J, air resistance has done a work W = nc1