Category: General Physics
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Least Force Need for Application
A professor’s office door to 0.91 m wide, 2.0 m high, and 4.0 cm thick; has a mass of 25kg; and pivots on frictionless hinges. A “door closer” is attached to the door and the top of the door frame. When the door is open and at rest, the door closer exerts a torque of…
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Angular Positions of a clock
1) What is the angular position in radians of the minute hand of a clock at 5:00? To start this problem, you have to pay close attention to what they are asking: “the minute hand”. It is assumed that from 9 to 3 on the clock would make a 180 ° angle. The minute hands points at…
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What is the Angular Displacement during a Time Interval?
A child on a merry-go-round takes 3.1 s to go around once. What is his angular displacement during a 1.0 s time interval? “The period (T) is the duration of one cycle in a repeating event” Known Variables: Period: T=3.1 seconds Time: t= 1.0 second In order to find Angular displacement(Δθ), we need angular speed. First step is to find Angular speed (ω). ω=2π/T 2π/3.1=…
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What is the Angular Position?
A Ferris wheel rotates at an angular velocity of 3.9×10-2 rad/s . At t=0, your friend Seth is at the very top of the ride. What is Seth’s angular position at t= 3.4 min measured counterclockwise from the top? Give your answer as an angle in degrees between 0° and 360°. Known Variables: Angular Velocity (ω): 3.9×10-2 rad/s…
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What is the Speed?
A 5.0-m-diameter merry-go-round is initially turning with a 4.5 seconds period. What is the speed of a child on the rim? Known variables: diameter (d): 5.0 meters period (T): 4.5 seconds velocity (v)= circumference / period Circumference (c) = π x d π x 5.0= 15.707 m v=c/T v= 15.707 m /4.5 s v= 3.5m/s
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What is the Speed and Acceleration?
Your roommate is working on his bicycle and has the bike upside down. He spins the 62 cm-diameter wheel, and you notice that a pebble stuck in the tread goes by three times every second. What is the pebble’s speed? Known Variables: Angular speed: 3 rev Diameter (d) : 62 cm Convert angular speed to radians. 3…
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What is the Speed and Tension?
A 260 g block on a 60 cm-long string swings in a circle on a horizontal, frictionless table at 60 rpm. 1) What is the speed of the block? Known variables: Mass (m): 260 g or .26 kg Radius (r): 60 cm or .6m Period (T): 60 rpm Speed Equation v = ω r Convert to radians ω = 60 rpm Angular Velocity: ω=2π/T 60 x…
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Required Speed
You’re driving your pickup truck around a curve with a radius of 22 m . A box in the back of the truck is pressed up against the wall of the truck. How fast must you drive so that the force of the wall on the box equals the weight of the box? Known…
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What is the angle and Angular Speed?
The earth’s radius is about 4000 miles. Kampala, the capital of Uganda, and Singapore are both nearly on the equator. The distance between them is 5000 miles. Through what angle do you turn, relative to the earth, if you fly from Kampala to Singapore? α =5000/4000 =1.25rad => α= 1.25*180/π = 71.62o 2) The flight from…
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RPM to Radians
A turntable rotates counterclockwise at 78 rpm. A speck of dust on the turntable is at 0.44 rad at t=0 ,What is the angle of the speck at t = 7.9 s? Your answer should be between 0 and 2π rad. Convert rpm in radians ω = 78rpm = 78*2π/60s = 8.164 rad/s angular displacement when t = 7.9s θ = 8.164 rad/s * 7.9 = 64.49…