An electrical water heater (for room heating) held at 140of is kept in a 70of room. when purchased, its insulation is equivalent to r-5. an owner puts a 25-ft2 blanket on the water heater, raising its total r value to 15. assuming 100 percent conversion of electricity into heated water, how much energy (kwhr) will be saved each year? if the electricity costs 8.0 cents/kwhr, how much money will be saved in energy each year?

One hazard of space travel is debris left by previous missions. there are several thousand masses large enough to detect by radar orbiting the earth, but there are far greater numbers of very small masses such as flakes of paint. calculate the force exerted by a 0.110 mg chip of paint that strikes a space shuttle window at a relative speed of 5.00 ✕ 103 m/s and sticks, given the collision lasts 6.00 ✕ 10-8 s. such a collision chipped the window of the ill-fated challenger in june 1983, causing $50,000 of damage.