Solve the following problems: (3pts each) 1. Calculate the power of a car brake that it is capable of doing 40000J of work in 5 s when stopping the car.
2. Kram can lift a 40.0-kg sack of rice at a height of 0.10 m 15 times in 1 minute. What is Kram’s power output?
3. How much work is done in lifting an object that weighs 250N to a height of 4m?
4. How much power is exerted if the 250N object is lifted to a height 4m in 4s?
5. While doing a chin-up, Gina lifts her 45.0-kg body to a height of 0.25 meters in 5 seconds. What is the power delivered by Gina's biceps?

need to see circuit to get time constant

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.