You would like to freeze a surgically removed 5.0 cm diameter spherical brain tumor. in order to avoid the formation of large ice crystals within the tumor, you would like to keep the temperature within the tumor spatially uniform. tissue properties: constant thermal conductivity = 0.64 w/m*k, thermal diffusivity = 2.5 x 10-7 m2/s. (a) determine an appropriate h in order to meet this criteria. (b) how long will the tumor take to freeze, i. e. reach 0°c, if placed in a -20°c freezer using the h found in part (a).

Suppose you have three polarizing filters, with the second at an angle of 42∘ to the first and the third at an angle of 90∘ to the first. by what perfect will the original intensity of unpolarized light be reduced to after passing through all three filters?

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

You are a sales representative for a company that makes a new alternate fuel for vehicles. you have prepared a presentation for the environmental engineers to sell your new product. what question do you expect the audience to ask regarding whether the new fuel will cause less damage to the environment? a. do we have to change any parts of the vehicle to use this alternate fuel? b. will the vehicles get better fuel mileage with the alternate fuel? c. how much greenhouse gas does your fuel produce compared with current fuel sources? d. is the alternate fuel more expensive than fossil fuel?