A particle moves along the x axis. Its position varies with time according to the expression x=-4t +2t^2, where x is in meters and t is in seconds.3 The
position–time graph for this motion is shown in Figure 2.4a. Because the
position of the particle is given by a mathematical function, the motion of
the particle is completely known, unlike that of the car in Active Figure 2.1.
Notice that the particle moves in the negative x direction for the first second
of motion, is momentarily at rest at the moment t=1 s, and moves in the
positive x direction at times t=1 s.

(C) Find the instantaneous velocity of the particle at t 5 2.5 s.

Acoal-fired plant generates 600 mw of electric power. the plant uses 4.8 x 10^6 kg of coal each day, and the heat of combustion of coal is 3.3x 10^7 j/kg. the steam that drives the turbines is at a temperature of 300° c, and the exhaust water is at 37° c. (a) what is the overall efficiency of the plant for generating electric power? (b) how much thermal energy is exhausted each day? (c) what is the change in entropy of the universe for this heat engine? (d) using the same heat reservoirs, what is the maximum possible (carnot) efficiency for a heat engine?

Aray of light traveling parallel to the principal axis of a concave mirror will be reflected through the mirror's

The intensity of a polarized electromagnetic wave is 12 w/m^2. part a) what will be the intensity after passing through a polarizing filter whose axis makes the angle θ=0∘ with the plane of polarization? part b) what will be the intensity after passing through a polarizing filter whose axis makes the angle θ=30∘ with the plane of polarization? part c) what will be the intensity after passing through a polarizing filter whose axis makes the angle θ=45∘ with the plane of polarization? part d) what will be the intensity after passing through a polarizing filter whose axis makes the angle θ=60∘ with the plane of polarization? part e) what will be the intensity after passing through a polarizing filter whose axis makes the angle θ=90∘ with the plane of polarization?