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Questions in physics

[Answered] An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?

[Answered] In which of the following units is acceleration expressed? A. Kilograms B. Meters per second squared C. Foot-pounds D. Newtons

[Answered] What is the energy of a photon with a frequency of [tex]$2.2 \times 10^{16} Hz$[/tex]? Planck's constant is [tex]$6.63 \times 10^{-34} J \cdot s$[/tex]. A. [tex]$1.5 \times 10^{-17} J$[/tex] B. [tex]$8.8 \times 10^{-17} J$[/tex] C. [tex]$1.5 \times 10^{-16} J$[/tex] D. [tex]$8.8 \times 10^{-16} J$[/tex]

[Answered] An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?

[Answered] Why do you think bacteria can live in your digestive system without making you sick?

[Answered] Two steel blocks rest on a frictionless, horizontal surface. Block X has a mass of 6.0 kg and is attached by means of a light taut string to block Y that has a mass of 12 kg. A force of 36 N [E] is applied to block X as shown below. Calculate the force block Y exerts on block X.

[Answered] Assume that you have a mass of [tex]50.0 \, \text{kg}[/tex] and Earth has a mass of [tex]5.97 \times 10^{24} \, \text{kg}[/tex]. The radius of Earth is [tex]6.38 \times 10^{6} \, \text{m}[/tex]. What is the force of gravitational attraction between you and the Earth?

[Answered] Will all the bulbs have the same brightness in a series circuit, regardless of how many there are? Does the number of bulbs affect their brightness?

[Answered] Physics Help It is estimated that 1.0 kg of body fat will provide [tex]3.8 \times 10^7 \, \text{J}[/tex] of energy. A 60-kg mountain climber decides to climb a mountain 4000 m high. (a) How much work does the climber do against gravity in climbing to the top of the mountain? The answer for this is [tex]2.4 \times 10^6 \, \text{J}[/tex]. (b) If the body’s efficiency in converting energy stored as fat to mechanical energy is 25%, determine the amount of fat the climber will use up in providing the energy required to work against the force of gravity. The answer is [tex]0.25 \, \text{kg}[/tex]. I got (a) but I don't understand how to do (b).

[Answered] The energy required to lift two skiers to the top of the mountain is 240,000 J. The electric motor has an efficiency of 40%. Calculate the energy wasted in the motor.