I have absolutely no idea how to do any part of this problem, can anyone help? 7. A group of students, working in the physics lab, built an “Electromagnetic Vertical Launcher”. The apparatus includes an electric circuit with a 120 V battery, connected in series to a 100 Ω resistor, switch, and thin 500 g metallic rod that is placed on two horizontal conducting supports. The rod has a length of 40 cm and is placed in a uniform horizontal 1.5 T strong magnetic field. a). On the diagram below show all the applied forces on the rod when the switch is closed. b). Find the normal force in each support when the switch is closed. c). What is the minimum voltage has to be applied in order to keep the rod weightless? d). The resistor is replaced with much smaller value of 5 Ω resistor. When the switch is closed find the instantaneous acceleration of the rod.

In a thunderstorm, charge builds up on the water droplets or ice crystals in a cloud. thus, the charge can be considered to be distributed uniformly throughout the cloud. for the purposes of this problem, take the cloud to be a sphere of diameter 1.00 kilometer. the point of this problem is to estimate the maximum amount of charge that this cloud can contain, assuming that the charge builds up until the electric field at the surface of the cloud reaches the value at which the surrounding air breaks down. this breakdown means that the air becomes highly ionized, enabling it to conduct the charge from the cloud to the ground or another nearby cloud. the ionized air will then emit light due to the recombination of the electrons and atoms to form excited molecules that radiate light. in addition, the large current will heat up the air, resulting in its rapid expansion. these two phenomena account for the appearance of lightning and the sound of thunder. take the breakdown electric field of air to be eb=3.00ă—106n/c. part a estimate the total charge q on the cloud when the breakdown of the surrounding air is reached. express your answer numerically, to three significant figures, using ďµ0=8.85ă—10â’12c2/(nâ‹…m2) .

Greg drew a diagram to compare two of the fundamental forces. which labels belong in the areas marked x, y and z? gravitational force electromagnetic force x. attractive y repulsive z: infinite range x: infinite range y attractive z. repulsive x. always attractive y: infinite range z: attractive or repulsive x. attractive or repulsive y infinite range z: always attractive

Amass weighing 24 pounds, attached to the end of a spring, stretches it 4 inches. initially, the mass is released from rest from a point 8 inches below the equilibrium position. find the equation of motion. (use g = 32 ft/s2 for the acceleration due to gravity.)