Vật dao động với phương trình 5cos(4pit+pi/6) tìm thời điểm đi qua vị trí biên dương lần thứ 4

An astronaut in space cannot use a scale or balance to weigh objects because there is no gravity. but she does have devices to measure distance and time accurately. she knows her own mass is 77.4 kg , but she is unsure of the mass of a large gas canister in the airless rocket. when this canister is approaching her at 3.50 m/s , she pushes against it, which slows it down to 1.30 m/s (but does not reverse it) and gives her a speed of 2.60 m/s . what is the mass of the canister?

Three resistors are connected in series across a 15-v power supply. if the potential drops across resistors 1 and 2 are 4.1 volts and 3.1 volts, what is the exact potential drop (in volts) across resistor 3?

Estimate the magnitude of the electric field due to the proton in a hydrogen atom at a distance of 5.29×10 to the power of −11 m, the expected position of the electron in the atom.