When a stone is dropped from a building 200 m high, its speed is proportional to the time elapsed after dropping. The distance traveled is proportional to the square of the time elapsed. After 1 second the speed of the train was 10 m/sec and it was 190 m above the ground. When its speed is 25 m/sec, what would be its distance from the ground?	Answers:
A) 140 m	B) 137.5 m	C) 125.75 m	D) 142.5 m	E) 152.5 m
v= x*t and s= y*t^2   10 = x*1, hence x=10 units   (200-190) = y*1*1   y=10   when speed = 25m/sec, time elapsed = 25/10= 
<gadget id="calculator">25/10</gadget>
<output>5/2 = around 2.5</output>
2.5 sec   distance travelled by stone= 10*(2.5)^2 = 62.5 mts   so distance of stone above ground = 200-62.5= 
<gadget id="calculator">200-62.5</gadget>
<output>137.5</output>
137.5 mtrs   ANSWER:137.5 m
<result>B</result>
When a stone is dropped from a building 200 m high, its speed is proportional to the time elapsed after dropping. The distance traveled is proportional to the square of the time elapsed. After 1 second the speed of the train was 10 m/sec and it was 190 m above the ground. When its speed is 25 m/sec, what would be its distance from the ground?