Shielded Ball Bearings
Shielded Ball Bearings
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 800 Skateboard in line Skate Black Shielded Deep Groove Radial Ball Bearings  US $385.00
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 800 Skateboard in line Skate Shielded Deep Groove Radial Ball Bearings US $344.00
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 1000 Skate Bearing 608 2Z 8x22x7 Shielded Ball Bearings US $259.00
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 1000 Skate Bearing 608 RZ 8x22x7 Shielded Ball Bearings US $259.00
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 6919ZZ Shielded 95x130x18 95mm 130mm 18mm 6919Z Deep Groove Radial Ball Bearings US $174.95
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 6818ZZ 90x115x13 Shielded 90mm 115mm 13mm 6818Z Deep Groove Radial Ball Bearings US $93.36
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 6819ZZ Shielded 95x120x13 95mm 120mm 13mm 6819Z Deep Groove Radial Ball Bearings US $83.02
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 6916ZZ Shielded 80x110x16 80mm 110mm 16mm 6916Z Deep Groove Radial Ball Bearings US $78.41
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 6918ZZ Shielded 90x125x18 90mm 125mm 18mm 6918Z Deep Groove Radial Ball Bearings US $75.90
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 6817ZZ Shielded 85x110x13 85mm 110mm 13mm 6817Z Deep Groove Radial Ball Bearings US $73.02
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 6314ZZ Ball Bearings 70mm 150mm Shielded 6314Z 6314 ZZ US $71.94
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 50 Bearing R168Z 1 4x3 8x1 8 Shielded Ball Bearings US $69.95
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 50 Bearing R166Z 3 16x3 8x1 8 Shielded Ball Bearings US $69.95
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 6915ZZ Shielded 75x105x16 75mm 105mm 16mm 6915Z Deep Groove Radial Ball Bearings US $68.36
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 10 Ceramic 3x6 Shielded 3x6x25 Miniature Deep Groove Radial Ball Bearings US $62.00
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 10 Ceramic 5x8 Shielded 5x8x25 Miniature Deep Groove Radial Ball Bearings US $62.00
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 10 Ceramic 6700ZZ 10x15x4 10mm 15mm 4mm 6700Z Ball Shielded Radial Ball Bearings US $62.00
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 100 X MR105 5 x 10 x 4mm Double Shielded Ball Bearings Deep Groove Ball Bearing US $61.86
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 6216ZZ 80x140x26 Shielded 80mm 140mm 26mm 6216Z Deep Groove Radial Ball Bearings US $60.90
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 6313ZZ 65x140x33 Shielded 65mm 140mm 33mm 6313Z Deep Groove Radial Ball Bearings US $60.90
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 10 Bearing Ceramic 58 Shielded mm Metric Ball Bearings US $59.95
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 10 Bearing Ceramic 36 Shielded mm Metric Ball Bearings US $59.95
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 63142Z Ball Bearings 70x150x35 Shielded Ball Bearings US $59.95
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 50 Bearing R4Z 1 4x5 8x0196 Shielded Ball Bearings US $59.95
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 6314ZZ 70x150x35 Shielded 70mm 150mm 35mm 6314Z Deep Groove Radial Ball Bearings US $59.95
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 10 Bearing Ceramic 850 Shielded 5mm x 8mm Ball Bearings US $59.95
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physics question?
In testing an new material for shielding spacecraft, 150 ball bearings each moving at supersonic speed of 400.0 m/s collide head-on and elastically with the material during a 1.00 min interval. If the ball bearings each have a mass of 8.0 g and the area of the tested material is 0.75 m^2, what is the pressure exerted on the material?
You can only provide an answer for the *average* pressure exerted on the material over the 1 minute interval. Obviously, the instantaneous pressure varies from zero, when no ball bearings are in contact with the material, to some high, but undefined pressure during the actual time of contact.
Before contacting the material, each Ball Bearing has a momentum of m*v, where m is the mass of the bearing and v is its velocity. After the collision, each ball bearing has a momentum of -m*v (they reverse direction). The total momentum must be conserved in these interactions, so
m*v = -m*v + momentum of material
momentum of material = 2*m*v
Each collision therefore imparts an impulse (a change in momentum) of 2*m*v to the material.
Force is defined as the change in momentum per unit time:
F = dp/dt
The average force (call this
In this case, the total change in momentum of the material caused by the impacts of 150 bearings is:
delta-p = 150 * 2*m*v
delta-p = 150 * 2* (8.0*10^-3 kg) * (400.0 m/s)
delta-p = 960 N*s
This occurs over a time of 1 min = 60 sec, so the average force is:
This force is exerted on an area of 0.75 m^2, so the average pressure is:
=
= 21.3 N/m^2
= 21 Pa (reported to the correct number of significant digits for the data given in this problem)
Laakerin suojalevyjen poisto. Taking out shields from ball bearing.