The diagrams below show a model airplane. propeller
propeller
rubber
number
hand
before winding
rubber band
after winding
rubber band
Which energy transformation occurs in a rubber band powered model airplane when it is flown?
Thermal energy stored in the rubber band is transformed into chemical energy used by the propeller.
Kinetic energy stored in the rubber band is transformed into thermal energy used by the propeller.
Chemical energy stored in the rubber band is transformed into potential energy used by the propeller.
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Potential energy stored in the rubber band is transformed into mechanical energy used by the propeller.

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) .

In which type of system is power held solely by the central government and not shared with regional governments? group of answer choices federal unitary confederate oligarchic

Carmen is load furniture and boxes onto a moving truck. she picks up boxes of her things, places them on a cart, and pushes the cart to the moving van. which term best describes the type of force carmen uses? a. contact b. friction c. gravity d. noncontact