13–82. the 8-kg sack slides down the smooth ramp. if it has a speed of 1.5 m> s when y = 0.2 m, determine the normal reaction the ramp exerts on the sack and the rate of increase in the speed of sack at this instant.
y
*13–84. the 2-lb block is released from rest at a and slides down along the smooth cylindrical surface. if the attached spring has a stiffness k = 2 lb> ft, determine its unstretched length so that it does not allow the block to leave the surface until u = 60°.
a
prob. 13–82
prob. 13–84
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Aplane flying horizontally at an altitude of 1 mile and a speed of of 500mih passes directly over a radar station. find the rate at which the distance from the plane to the station is increasing when it is 2mi away from the station.

Ascientist is working with a new kind of quantum dot to make a dye. he is applying newton’s laws to the particle, but it seems to be breaking these laws of physics. which action will most likely the scientist study the particle’s motion? a. he needs to remember that the particle is too large for quantum analysis. b. he must continue to use newtonian mechanics, but he needs to learn more about the particle. c. he needs to use quantum mechanics, not newtonian mechanics, because this is a nanotechnology product. d. he must determine new physical laws that only apply to quantum dots.

1) a child holds two dogs on two separate leads. the dogs are pulling in different directions. one is pulling a force of 20n north and one is pulling 15n eastwards. calculate the resultant force on the child. state the direction. (use the parallelogram of forces) 2) a force of 20n acts horizontally on an object. a second force of 5n acts at 60 degrees to the first one. calculate the resultant force. worth 20 points, need answers asap with method you x