REVIEW. 181 



4. Give (a.) the facts and (6.) the laws of gravity. A body weighs 

 1440 Ibs. at the surface of the earth ; (c.) how far above the surface 

 will its weight be 90 Ibs. ? (d.) What will it weigh 2200 miles 

 below the surface ? 



5. (a.) What is a machine? (&.) What is a foot pound? (c.) Tell 

 how the advantage gained by a simple mechanical power is found ; 

 and (d.) show this by an illustration of your own. (e ) Explain the 

 cause of friction. 



6. (a.) What is a simple pendulum ? (6.) What is an oscillation? 

 (c.) How does a change of latitude change the number of vibrations ? 

 (d.) Why? 



7. (.) What is the length of a second's pendulum ? (6.) What 

 is the length of one vibrating | seconds ? 



8. (a.) State the general law of machines, and (6.) illustrate it by 

 means of the pulley. 



9. (a.) What is the centre of gravity ? (6.) How found? 



10. (a.) Draw figures illustrating the position of parts in the dif- 

 ferent kinds of levers ; (6.) make and solve a simple problem in 

 each. 



11. (a.) What is the relation which the length of a pendulum 

 bears to its time of oscillation ? (6.) Give the length of a pendulum 

 beating once in 2i seconds. 



12. (a.) Give the second and third laws of motion, and (&.) illus- 

 trate them. 



13. A and B, at opposite ends of a bar 6 ft. long, carry a weight 

 of 600 pounds suspended between them. A's strength being twice 

 as great as B's, how far from A must the weight be suspended ? 



14. (a.) Give the formulas for falling bodies, (&.) translating them 

 into common language. (c.) Give the same for bodies rolling 

 freely down inclined planes. A body fell from a balloon one mile 

 above the surface of the earth ; (d.) in what time, and (e.) with what 

 velocity would it reach the earth ? 



15. A ball thrown downward with a velocity of 35 feet per second 

 reaches the earth in 12 i seconds, (a.) How far has it moved, and 

 (&.) what is its final velocity ? 



16. (a.) A bricklayer's laborer with his hod weighs 170 pounds ; 

 he puts into the hod 20 bricks weighing 7 pounds each ; he then 

 climbs a ladder to a vertical height of 30 feet. How many units of 

 work does he? (&.) If he can do 158,100 units of work in a day, 

 how many bricks will he take up the ladder in a day ? 



17. Define three accessory properties of matter. 



18. How much weight will a cubic meter of any solid lose when 

 weighed (a.} in hydrogen? (&.) in air? (c.) in carbonic acid gas? 



