Mindblown: a blog about philosophy.
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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…
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What is the Speed?
The blade on a table saw spins at 3650 rpm. Its diameter is 25.0 cm.? a) What is the speed of a tooth on the edge of the blade in m/s? Angular speed w = 3650 rpm = 3650 * 2*pi rad / 60 s = 382.22 rad / s Diameter d = 25 cm radius r = d / 2…
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Centripetal Acceleration
To withstand “g-forces” of up to 10 g’s, caused by suddenly pulling out of a steep dive, fighter jet pilots train on a “human centrifuge.” 10 g’s is an acceleration of 98 m/s2 If the length of the centrifuge arm is 15.0 m, at what speed is the rider moving when she experiences 10…
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What is the magnitude of the net force?
A 1300 kg car drives around a flat 180 m-diameter circular track at 22 m/s. What is the magnitude of the net force on the car? Fc= m * ac = m * v2/r =1300 * (22)2/(180/2) = 6991 =7000 N
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What is the Centripetal Acceleration and Magnitude?
A fast pitch softball player does a “windmill” pitch, moving her hand through a vertical circular arc to pitch a ball at 68 mph. The 0.20 kg ball is 55 cm from the pivot point at her shoulder. 1) Just before the ball leaves her hand, what is its centripetal acceleration? ( 68 mph…
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What is the acceleration from the axis of rotation?
A typical laboratory centrifuge rotates at 4000 rpm. Test tubes have to be placed into a centrifuge very carefully because of the very large accelerations. 1) What is the acceleration at the end of a test tube that is 10 cm from the axis of rotation? Ac = v2/r The radius is 10cm or .10m The…
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What is its Orbital Period?
An earth satellite moves in a circular orbit at a speed of 7000m/s? What is its orbital period? r = GM/v2 r: distance of the satellite from the center of Earth in m M is the mass of Earth: 5.974 x 1024 v is the orbital speed: 7000 m/s r = 6.674x 10-11 x 5.974 x 1024/70002 r = 8137445…
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