







Covering a site with 6 inches of rock 
20160426 

From Carla: if a pump house that measures 20'x16' sits in the middle of a site that is 50'x60' and you apply crushed rock to the site at depth of 6", how many yards will you need to haul? Answered by Penny Nom. 





Filling a hole with 14 tons of rock 
20160408 

From Barry: If I had 14 tons of inch and one half sized aggregate rock, how large of a square or rectangular shaped hole would I need to hold that amount? Answered by Penny Nom. 





A camera's line of sight 
20110226 

From MJ: A rocket that is rising vertically is being tracked by a ground level camera located 3 mi from the point of blast off when the rocket is 2 mi high its speed is 400mph At what rate is the (acute) angle between the horizontal and the camera's line of sight changing Answered by Penny Nom. 





When will the rocket hit the ground? 
20070405 

From Megan: A model rocket is launched at an upward velocity of 460feet per second off a platform that is 40 feet up from the ground. Use the formula h(t)= 16+vo+ho where vo is the initial velocity an ho is the initial height.
A.) Find the maximum hight of the rocket.
B.) How long does it take to reach the maximum height?
C.) When will the rocket hit the ground? Answered by Stephen La Rocque. 





I need to fill an area with rock 
20050304 

From Kelly: if I need to fill an area with rock that is 64 feet long by 4 feet wide and 1 foot 2 inches in depth
how many tons of rock will this job require?
it is also sold by cubic yard how many of these cubic yards will I need? Answered by Penny Nom. 





A rock on a string 
20031026 

From A student: a rock on a 4' string is rotated at 80 rpm. what is the linear speed in feet per second? in miles per hour? Answered by Penny Nom. 





A two stage rocket 
20021126 

From Hoda: a two stage rocket accelerates in free space by ejecting fuel at a constant relative speed , v(ex). the full fuel load makes up 80% of the initial mass of the entire two stage rocket . the rocket accelerates from rest until at the end of the first stage when 75% of its fuel has been burnt. find an expression for the speed of the rocket at the end of the first stage in terms of v(ex). Answered by Claude Tardif. 





Calculer la hauteur de chute de cette pierre 
20001216 

From Marcus: Une pierre tombe au fond d'un puit, ŕ 5 secondes on entend un son (de la pierre). Calculer la hauteur de chute de cette pierre en tenant compte de la vitesse du son = 340m.s^{1} Il faut savoir que pour la chute libre v= g.t ; h = 1/2 g.t^{2} ; v = 2g.h g intensité du champs de pesanteur = 10 ; h hauteur de chute. Answered by Claude tardif. 

