A porch roof that slopes upward at 45° measures 3.0 m × 5.0 m. It is covered with a slab of insulating material that is 2.0 cm thick
If the density of the insulation is 15 kg/m3, what is the weight of the insulation, in pounds, on the roof? (1.00 kg weighs 2.2 lb and density is mass per unit volume.)
A) 4.5 lb
B) 9.0 lb
C) 20 lb
D) 990 lb
E) 9.9 lb
E
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A lawn mower has a 6-horsepower engine (1 HP = 750 W). If the engine has an efficiency of 20%, and the throttle is such that the engine cycles 10 times a second, the heat that is expelled in one cycle is
A. 1 800 J B. 2 000 J C. 2 200 J D. 2 400 J E. 2 250 J
A solid sphere of mass 2.5 kg and radius 0.12 m starts from rest at the top of a ramp inclined 15° and rolls to the bottom. The upper end of the ramp is 1.2 m higher than the lower end. What is the linear speed of the sphere when it reaches the bottom of the ramp? (Note: I = 0.4MR2 for a solid sphere, and g = 9.8 m/s2.)
a. 4.1 m/s c. 3.4 m/s b. 4.7 m/s d. 2.4 m/s
Suppose a nucleus has 50 protons and 50 neutrons. This places the nucleus to the right of the line of stability; therefore, it will most likely undergo radioactive decay. Given its place on the plot, what are the most likely types of radioactive decay?
a. Alpha decay. b. Beta plus decay and electron capture. c. All of the above. d. Gamma emission. e. None of the above, because the nucleus is stable.
When a body moves with uniform acceleration, the net force on it is zero
Indicate whether the statement is true or false