2 AJVSWJSBS TO PRACTICAL QUESTIONS 



5. Suppose you were on a train of cars moving at, the 

 rate of SO miles per hour ; ivith ^vhat force ^vould you be 

 thrown forward if the train vvere stopped instantly ? 



With the same velocity which the train had, or 44 feet per 

 second. Your momentum would be your mass multiplied by 

 this velocity. 



0. In what line does a stone fall from the mast-head of 

 a vessel in motion ? 



In a slightly curved line, produced by the two forces grav- 

 ity and the forward motion of the vessel. 



7. If a ball be dropped from a high tower it ivill strike 

 the earth a little east of a vertical line. Why is this ? 



In the daily revolution of the earth on its axis, from west 

 to east, the top of the tower moves faster than the bottom, be- 

 cause it passes through a larger circle. "When, therefore, the 

 ball falls, it retains that swifter easterly motion, and so strikes 

 very slightly east of the vertical. 



8. It is stated that a suit was once brought by the driver 

 of a light wagon against the owner of a coach for damages 

 caused by a collision. The complaint was that the latter 

 was driving so fast, that when the two carriages struck the 

 driver of the former was throivn forward over the dash- 

 board. Show how his own testimony proved him to have 

 been at fault. 



When the light wagon was suddenly stopped, its driver went 

 on with the same speed at which the wagon was moving. That 

 this threw him forward over the dash-board, proves his speed 

 to have been unusual. 



9. Suppose a train moving at the rate of 3O miles per 

 hour ; on the rear platform is a spring-gun aimed parallel 

 'with the track, and in a direction precisely opposite' to the 

 motion of the car. Let a ball be discharged with the exact 

 speed of the train, where would it fall ? 



In a vertical line to the track. The two equal, opposite mo- 

 tions would exactly destroy each other. 



