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course phy 201
10/17 12:00 am
`q001. For each of the given objects on the various inclines estimate, based on a sketch as opposed to a formula, the parallel and perpendicular components of the object's weight as a percent of its weight. Use your estimated percents to find the component of each weight parallel to the incline, and perpendicular to the incline. A car weighing 20 000 Newtons on an incline making angle 12 degrees with horizontal.
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y=80%=1600N perpendicular
x=20%=4000N parallel
@& Not bad, but the percents will always add up to more than 100, unless one of them is zero (in which case the other will be 100%).*@
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A hotwheels car of weight 80 000 dynes on an incline whose angle with horizontal is 20 degrees.
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y=70%=56000 dynes perpendicular
x=40%= 32000 dynes parallel
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A block of weight 30 pounds on a 37 degree incline.
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y=70%=21 lbs. perpendicular
x=60%=18 lbs. parallel
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`q002. If the car in the first question experiences a frictional force which is 2% of the perpendicular component of its weight, then what is the magnitude of the frictional force?
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16000N* .02= 320 N
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If the car is coasting downhill what is the sum of the parallel component of its weight and the frictional force?
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16000N - 320N= 15680N
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If the car is coasting uphill what is the sum of the parallel component of its weight and the frictional force?
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16000N - 320N= 15680N
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`q003. If the hotwheels car in the first question is attached by a light thread to a washer weighing 20 000 dynes and suspended over a pulley at the lower end of the ramp, then if friction is ignored what is the net force acting in the direction down the ramp?
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32000+20000=52000 dynes
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Answer the same question assuming that the washer is suspended from a pulley at the top of the ramp.
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32000 dynes- 20000dynes= 12000 dynes
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`q004. How much frictional force would it take to hold he block in the first question stationary on the incline?
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18 lbs
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What is this force as a percent of the weight of the block?
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60%
@& Very good. Check my note(s).*@