(1) If the temperature of the body is 90°C to falls to 70°C in 5 minutes when placed in a surrounding of constant temperature 20°C, calculate the time for the temperature of the body to become 50°C. Find the k constant. (2) Apply Snell's law when light travels from air (n = 1.0003) to a flint glass (n = 1.56) where Oi = 30° (3) A 5-cm-high object is placed in front of a concave mirror with a radius of curvature of 20 cm. Determine the image height if the object's distance is 30 cm. the other cons

Humans are unable to convert radiant energy from the sun into stored energy that can be usedto do work. Plants, however, obtain their energy from photosynthesis – sunlight is used toconvert carbon dioxide and water into sugars (stored as an energy source) and oxygen.Consider a leaf with a surface area of 2.5 cm2. On a sunny day it might receive sunlight withan average power per unit area of 350 W/m2. Of this incident light, only about 40% is usefulfor photosynthesis. (a) If the process was perfectly efficient (i.e. all the useful radiation was converted tostored internal energy), calculate the increase in internal energy of the leaf in aperiod of one hour. (b) In practice, the overall efficiency of the process (percentage of energy storedrelative to the total incident energy reaching the surface of the leaf) is only about6%. Discuss, in relation to the First Law of Thermodynamics, what happens to theremaining energy?

Total internal reflection: The speed of light in a material is 0.39c. What is the critical angle of a light ray in degrees at the interface between the material and a vacuum? (keep 2 sig figs please)