







Golf for 10 
20120418 

From Bob: Question from Bob:
Hi,
I am trying to set up pairings for 4 rounds of golf with only 10 golfers (2 foursomes and 1 twosome) and trying to minimize duplications. Any formulas or help? Answered by Victoria West and Harley Weston. 





Finding Force When Pressure and Area Are Known 
20090625 

From chris: i need to calculate the force for a tube. given the follwing data.
pressure is 900 PSI
Tube is 6 m long by 1.5m Outside Diameter Answered by Janice Cotcher. 





Apparent Weight in salt water 
20090606 

From Rob: If an object weighs 100kg in air how much will it weigh when suspended in salt water?
Is there an easily used conversion calculation? Answered by Janice Cotcher. 





Unit Conversion for Force and Mass 
20090508 

From Ray: Good Day! I was confused about lbm and lbf and slug. I knew that lbm is a unit
for mass and lbf is a unit for weight. my problem is some books follow this
relationship where lbf=(lbm times the gravitational pull) which is 32.2 ft/(s^2)
while other books treat lbm=lbf. other books also treat lbm=(lbf times 32.2)...
which is correct?
Is 1kg=2.205 lbm or 1kg=2.205lbf?
Is 1BTU=778.16 lbfft or 1BTU=778.16 lbmft?
what is the relationship of slug on these two, lbm and lbf? Answered by Janice Cotcher. 





Pressure at Given Depth 
20090222 

From Tamara: A sea is 3km deep. The average density of sea water there is 1020 kg/m^3. What is the water pressure at the bottom? Answered by Janice Cotcher. 





A force vector 
20080828 

From moumita: F=20N...this force is acting along a vector A=4j+3k.what is F? Answered by Penny Nom. 





Two forces acting on a body 
20080621 

From Rita: Before answering the question below, what exactly is, in basic words, resultant force?
QUESTION:
Two forces of 50 and 68 pounds act on a body to produce a resultant force of 70 pounds.
Find, to the nearest 10 minutes or nearest tenth of a degree, the angle formed between the resultant force and the smaller force. Answered by Harley Weston. 





Hoisting an anchor 
20080110 

From ron: four men on a boat are using a capstan for hoisting an anchor weighing 2000lbs. The diameter of the barrel of the capstan at the section in use is 8in., and the pull on the chain carrying the anchor and passing around the capstan barrel is assumed to act at a distance of 1in. from the surface of the barrel. If the distance from the axis of the barrel to each point at which effort is applied to a capstan bar is 40in., what force must be applied by each man hoisting the anchor? Answered by Stephen La Rocque. 





Forces on an inclined plane 
20080110 

From Ron: A body that weighs 540lbs is caused to slide up an inclined plane with a uniform velocity by a force that acts parallel to the plane. For each foot of horizontal distance, there is a vertical rise of 2in. If the coefficient of sliding friction is 0.16, what force is required to move the body? Answered by Stephen La Rocque. 





How do you calculate work when force is negative? 
20071002 

From Snigdha: how do you calculate work when force is negative? Answered by Stephen La Rocque. 





The tension in a single strand of wire 
20070813 

From Gene: Seeking an equation that calculates the tension in a single strand of wire or rope. Conditions: the wire is fixed at both ends, A known weight is suspended from the center of the span. The weight will dipslace the strand downward some distance Y. Let the distance between the fixed ends be X= 500mm. Weight W=0.5kg. Original tension in the strand is T= 10 newtons.Your help sincerely appreciated. Answered by Gabriel Potter and Stephen La Rocque. 





4 digit lock 
20070516 

From Kathy: Hi,
My name is Kathy and I'm a REALTOR, I have 2 different lockboxes that
I cannot remember the combinations for, so what I need is all the
different combinations for 4 digits that cannot be the same, i.e. 0123.
Can you help me out? I would hate to throw them away as they cost
about $30 each.
Thank you,
Kathy Answered by Stephen La Rocque. 





A couch sliding off a truck 
20070430 

From William: A couch with a mass of 1 X 10^2kg is placed on an adjustable ramp connected to a truck. As one end of the ramp is raised, the couch begins to move downward. If the couch slides down the ramp with an acceleration of .70 meters per second when the ramp angle is 25 degrees, what is the coefficient of kinetic friction between the ramp and couch?
I drew a force diagram and if I did it correctly I identified the forces involved as "mg" (mass x gravity), "Fn" (normal force) and the "Ff" (frictional force). I know that we have the couch sliding down the ramp a .70 m/s but I don't think this a force and I'm not sure how this info fits into the problem. I know that the formula for calculating the coefficient of friction is Ff/Fn. Based upon the force diagram I drew and calculated Fn to be 1082N. I can't seem to get past this point. How do I determine what the frictional force is? Answered by Stephen La Rocque. 





Friction of a skier 
20070324 

From William: An olympic skier moving at 20.0 m/s down a 30 degree slope encounters a region of wet snow and slides 145m before coming to a halt. What is the coefficient of friction between the skis and the snow? Answered by Stephen La Rocque. 





Rotorride 
20070307 

From Jessie: In a "Rotorride" at a carnival, people are rotated in a cylindrically walled "room". The room radius is 4.6m and the rotation frequency is 0.550 revolutions per second when the floor drops out. What is the minimum coefficient of static friction so that people will not slip down? People on this ride say they were "pressed against the wall". Is there really an outward force pressing them against the wall? If so, what is its source? If not, what is the proper description of their situation (besides scary)? Answered by Stephen La Rocque. 





A person jumps from the roof of a house 
20070213 

From Jessie: A person jumps from the roof of a house 3.9m high. When he strikes the ground below, he bends his knees so that the torso decelerates over an approximate distance of 0.70m. If the mass of his torso (excluding legs) is 42kg, find a) his velocity just before his feet strike the ground , and b) the average force exerted on his torso by his legs during deceleration.
Please provide calculations and answers for comparison. Answered by Stephen La Rocque. 





The angle between two forces 
20050119 

From Abraham: One force of 20 pounds and one force of 15 pounds act on a body at the same point so that the resultant force is 19 pounds. Find, to the nearest degree, the angle between the two original forces. Answered by Penny Nom. 





The combined force of two vectors 
20041030 

From Brian: Two teams are playing push ball with a large 8 foot diameter ball. One team exerts a force represented by the vector a = 2i + 5j, and the other team exerts a force represented by the vector b = 8i3j.
1.Determine the direction of movement of the ball if the i axis is due east.
2.Determine the combined force magnitude. Answered by Harley Weston. 





The force of a 5000 tonne lorry 
20041027 

From Aaron: A 50 tonne lorry is parked on a slope with a gradient of 4%.
Due to the self weight of the lorry, what is the force
* acting down the slope
* acting normal (at right angles) to the slope Answered by Penny Nom. 





Levers 
19990113 

From Lane Campbell: 1. Solve for x or y. (a)
<4m><4m><xm >
_____________________________________________________
^ ^ ^ ^
25N 5N ^ 15N
Answered by Jack LeSage. 

