Suppose that the initial number of bacteria in a culture is 200, and that there are 700 bacteria present after 2 days. How long would it take for the number of bacteria to reach 4000?

You read in a popular diet blog that the author claims you can lose up to half a pound of body fat per week if, instead of drinking 1.9 liters (i.e., 1.9 kilograms) of water every day, you can eat the same amount of water in the form of ice. The reasoning is that your body must first melt the ice and then bring the ice water up to the body temperature of 37°C, which is a process that requires a significant amount of energy at the expense of “burned” body fat. Thankfully, you just finished discussing heat and phase changes in your physics class, so you can calculate exactly how much energy is expended. The specific heat and latent heat of fusion for water are 4.186 × 103 J/(kg⋅°C) and 3.34×105 J/kg, respectively a)  How many kilocalories do you expend when you eat 1.9 kg of ice at 0°C? Note that 1 kcal = 4186 J.  b) Assuming the metabolism of one pound of body fat produces 3500 kcal of energy, how many pounds of body fat could you lose in a week just by eating 1.9 kilograms of ice every…

19. The following fission reaction (shown below) occurs in a nuclear power plant. There are 1.50 x 1016 uranium-235 atoms that are simultaneously undergoing this reaction. The uranium is surrounded by 17.5 kg of heavy water, which has a specific heat capacity of 4.70 x 10³ J/kg °C. If 90% of the energy released in the nuclear reactions is absorbed as thermal energy by the heavy water, determine the increase in temperature of he heavy water. ✔✔✔✔ 235U+n→ Zr + 139 Te + 3(n) 92 40 52 mzr-94 = 93.906 u MTe-139 = 138.935 u Mu-235 = 235.044 u

Choose the correct answer 1. You have a 90 cm long iron rod at 15 ° C that heats up to 300 ° C. What happens with the rod is that: A. It melts. B. Double the length. C. Decrease its length a few centimeters. D. Increase its length by a few millimeters. 2. A student blows up a balloon and places it in his home freezer. After a long time, the balloon is removed from the freezer and it is observed that: A. The volume decreases as a certain amount of air escapes. B. It remains the same, because the air inside it does not expand or contract. C. The volume increases, because the air inside it expands D. The volume decreases as the air inside it contracts

4. Ideal Gas Type Question: A piston comprises two nested cylinders which are 3 cm and 2.8 cm in diameter with 0.1 cm thick walls and are each 1 m long. Initially, the smaller cylinder sits completely inside the larger cylinder and is filled with N2 at 20 °C and atmospheric pressure. a. C. The gas is slowly heated, while the cylinder is allowed to freely expand. What kind of process is this? banc b. The smaller cylinder has a total mass of 1.5 kg. What temperature does the gas need to be for the cylinder to become fully extended? The cylinder can withstand an internal pressure of 20 atm. What's the maximum weight it can lift? e. d. A 100 kg weight is dropped on the cylinder while it is fully extended, causing it to rapidly compress. What kind of process is this? If the cylinder is fully depressed by this event, what is the peak pressure? The adiabatic constant for N2 is 7/5. f. If the weight is dropped from 2 m, assuming 1% of its energy is converted into thermal energy in the gas,…

A hot air balloon uses the principle of buoyancy to create lift. By making the air inside the balloon less dense then the surrounding air, the balloon is able to lift objects many times its own weight. A large hot air balloon has a maximum balloon volume of 2090 m3. a.  If the air temperature in the balloon is 54 °C, how much additional mass, in kilograms, can the balloon lift? Assume the molar mass of air is 28.97 g/mol, the air density is 1.20 kg/m3, and the air pressure is 1 atm.

Water vapor at 100 degrees Celsius is put in contact with ice at 0 degrees Celsius and this mixture eventually results in 45 kg of liquid water at 30 degrees Celsius.  A. How many kilograms of ice were part of the mixture? B. How many kilograms of steam were part of the mixture?