1, [train of thought] this question is easy to wrong solution: W=I2Rt= (10 A) 2× 2ω ×10s=2000 J. The topic requires the calculation of the electric energy consumed by the motor for 10 s of normal operation, because the circuit does not convert all the electric energy into heat energy, in the calculation of electrical work can not be calculated with W=I2Rt, only W=UIt calculation (w=I2Rt is only a calculation of electric heat, which is only a part of the consumption of electric energy).
2, according to the pressure of the liquid from the formula P=hρg, known: ρ wine =0.8×10 kg/cubic meter. ρ mercury =16×10 kg/m3. A standard atmospheric pressure P=760mm mercury column,Request: h wine.
3, junior high school physics and mechanics occupy a high score, the investigation method is often based on physical calculations and physical experiments. The main knowledge points of physics and mechanics in junior high school are: the combination of motion and force, reference objects, mechanical motion, the effect of force, inertia and inertia law, two force balance, pressure (liquid pressure, atmospheric pressure), buoyancy, mechanical efficiency, kinetic energy and potential energy, mechanical energy and its transformation. This article is attached to the classical physics and mechanics calculation problems and experimental problems for students to learn.
4, the car is our familiar means of transportation, some transportation units in order to reduce operating costs wanton excess