Post on 17-Aug-2020
Physics Unit 3
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π½ =ππ β π2
π 2
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π = πΉπ cos ππ = 60 π 100 π cos 30Β° = 5196 π½
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π = πΉπ cos ππ = 200 π 100 π cos 90Β° = 0 π½
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F = 200 N (lift up)d = 2 m (down)
π = πΉπ cos π = 200 π 2 π cos 180Β° = β400 π½
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π = 0.075 ππ, π = 0.90 π, π£0 = 0π
π , π£π = 40
π
π π = πΎπΈπ β πΎπΈ0
πΉ 0.90 π =1
20.075 ππ 40
π
π
2
β1
20.075 ππ 0
π
π
2
πΉ 0.90 π = 60 π½πΉ = 66.7 π
4. Use π£2 = π£02 + 2π π₯ β π₯0 which becomes π£2 = 2πβ
6. 010. It would jump higher
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PE changes to KE
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π = πΉπππΈπ = ππ£πππππ ππππ 0 π‘π ππ₯ ππ¦ π»ππππβ²π πΏππ€ π₯
ππΈπ =1
2ππ₯ β π₯
ππΈπ =1
2ππ₯2
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π) π = πΉπ
π =1
2ππ₯2
π =1
22.22 Γ 105
π
π0.03 π 2 = 99.9 π½
π) πΎπΈπ + ππΈπ = πΎπΈ0 + ππΈ01
2ππ£π
2 +1
2ππ₯π
2 =1
2ππ£0
2 +1
2ππ₯0
2
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20.050 ππ π£π
2 + 0 = 0 +1
22.22 Γ 105
π
π0.03 π 2
0.025 ππ π£π2 = 99.9 π½
π£π2 = 3996
π2
π 2
π£π = 63.2π
π π) πΎπΈπ + ππΈπΊπ + ππΈππ = πΎπΈ0 + ππΈπΊ0 + ππΈπ0
At end of barrel1
2ππ£π
2 +ππβπ + 0 = 0 + 0 +1
2ππ₯0
2
1
20.050 ππ π£π
2 + 0.050 ππ 9.80π
π 20.03 π =
1
22.22 Γ 105
π
π0.03 π 2
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0.025 ππ π£π2 + 0.0147 π½ = 99.9 π½
0.025 ππ π£π2 = 99.8853 π½
π£π2 = 3995.412
π2
π 2
π£π = 63.2π
π At top of path
πΎπΈπ + ππΈπΊπ = πΎπΈ0 + ππΈπΊ01
2ππ£π
2 +ππβπ =1
2ππ£0
2 +ππβ0
0 + 0.050 ππ 9.80π
π 2βπ =
1
20.050 ππ 63.2
π
π
2
+ 0
0.49 ππ β π
π 2βπ = 99.9 π½
βπ = 204 π
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ππΈ0 + πΎπΈ0 = ππΈπ + πΎπΈπ
ππβ0 +1
2ππ£0
2 = ππβπ +1
2ππ£π
2
1500 ππ 9.8π
π 250 π +
1
21500 ππ 20
π
π
2
= 0 +1
21500 ππ π£π
2
π£π = 37.1 π/π
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πΈ0 +πππ = πΈπ1
2ππ£0
2 +ππβ0 +πππ =1
2ππ£π
2 +ππβπ
1
2200 ππ 0 2 + 200 ππ 9.8
π
π 20 +πππ
=1
2200 ππ 500
π
π
2
+ 200 ππ 9.8π
π 25000 π
πππ = 2.50 Γ 107 π½ + 9.80 Γ 106 π½πππ = 3.48 Γ 107 π½
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πΈ0 +πππ = πΈπ1
2ππ£0
2 +ππβ0 +πππ =1
2ππ£π
2 +ππβπ
0 + 1500 ππ 9.8π
π 210 π +πππ =
1
21500 ππ 12
π
π
2
+ 0
πππ = β39000 π½
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πΈ0 +πππ = πΈπ1
2ππ£0
2 +ππβ0 +πππ =1
2ππ£π
2 +ππβπ
0 + 0 + 800000 π½ =1
290 ππ π£π
2 + 90 ππ 9.8π
π 250 π
129.6π
π = π£π
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Unit named after James Watt who invented the steam engineIn the American system, horsepower is often usedOne horsepower is moving 550 pounds 1 foot in 1 second
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Power in the human body would be how quickly calories are being burnedLook at the table on page 166 to compare the power with the activity
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v0 = 0vf = 100 km/h = 27.78 m/st = 3.2 sm = 500 kg
π =π
π‘
π =
12ππ£π
2 β12ππ£0
2
π‘
π =
12 1000 ππ 27.78
ππ
2β 0
3.2 π = 121000 π
π = 1000π = 1 ππ, π‘ = 2 πππ =1
30β
π =π
π‘
1 ππ =π
130 β
π =1
30ππβ
πππ π‘ =1
30ππβ $0.10 = $0.0033
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From 2008 units are billions of kWh
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πΉΞπ‘ = ππ£π βππ£0
πΉΞπ‘ = 0.14 ππ 60π
π β 0.14ππ β40
π
π = 14 ππ π/π
πΉ =14 ππ
ππ
0.001 π = 14000 π
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πΉπ‘ = ππ£π βππ£0
πΉ 0.01 π = 0.001 ππ 0 β 0.001 ππ β15π
π
πΉ 0.01 π = 0.015 πππ
π πΉ = 1.5 π
πΉ 0.01 π = 0.001 ππ 10π
π β 0.001 ππ β15
π
π
πΉ 0.01 π = 0.025 πππ
π πΉ = 2.5 π
Hailstones are usually more massive than raindrops so that the force is even greater.The rebounding adds force to the collision
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The person has more mass than the bullet.Since they are half the mass, they will move at twice the speed. Mass and speed ratios are reciprocals.
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Usually only two objects for linear momentum because very rarely do more than two object hit at the same time. It usually happens that two hit, and then one of those hits another.Internal forces the objects pushing each otherExternal forces gravity pulling the objects down
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F12 and F21 are action-reaction pair from Newtonβs Third Law are equal and opposite
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Isolated system = no external forces
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π0 = πππ1π£01 +π2π£02 = π1π£π1 +π2π£π2
0.17 ππ 5π
π + 0.5 ππ 0
π
π = 0.17 ππ π£ + 0.5 ππ π£
0.85 πππ
π = 0.67 ππ π£
π£ = 1.27 π/π
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π0 = πππ1π£01 +π2π£02 = π1π£π1 +π2π£π2
5 ππ 0 + 0.15 ππ 0 = 5 ππ π£ + (0.15ππ)(35 π/π )0 = 5 ππ π£ + 5.25 ππ π/π β(5 ππ)π£ = β5.25 ππ π/π
π£ = 1.05 π/π
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4. One flies out5. Two fly out6. Three fly out7. Four fly out8. Canβt9. v10. mv is the same before and after
11. mv is the same before and after, but πΎπΈ =1
2ππ£2 will not be the same because of
the v2
πΎπΈ = πΎπΈ1
2π 2π£ 2 =
1
2ππ£2 +
1
2ππ£2
2ππ£2 β ππ£2
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Demo energy lost to heat by smashing two steel balls together
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SUV crash test videoNASCAR videoCrash test humor
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Momentumππ π£0π +πππ£0π = ππ π£ππ +πππ£ππ
0.1 ππ 1π
π + 0.05 ππ 0 = 0.1 ππ π£ππ + 0.05 ππ π£ππ
0.1 πππ
π = 0.1 ππ π£ππ + 0.05 ππ π£ππ
π£ππ = 1π/π β 0.5 π£ππKinetic Energy
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2ππ π£0π
2 +1
2πππ£0π
2 =1
2ππ π£ππ
2 +1
2πππ£ππ
2
1
20.1 ππ 1
π
π
2
+ 0 =1
20.1 ππ π£ππ
2 +1
20.05 ππ π£ππ
2
0.05 π½ = 0.05 ππ π£ππ 2 + 0.025 ππ π£ππ
2
π£ππ 2 + 0.5 π£ππ
2 = 1π
π
2
1π
π β 0.5π£ππ
2
+ 0.5 π£ππ2 = 1
π
π
2
1π
π
2
β 1π
π π£ππ + 0.25 π£ππ
2 + 0.5 π£ππ2 = 1
π
π
2
β 1π
π π£ππ + 0.75 π£ππ
2 = 0
π£ππ β1π
π + 0.75 π£ππ = 0
π£ππ = 0 ππ 1.33 π/π
π£ππ = 1π
π β 0.5 π£ππ
πππ = 1 π/π β 0.5(1.33 π/π ) = 0.333 π/π
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Do an actual demonstrationCollision
πππ£0π +ππ€π£0π€ = πππ£ππ +ππ€π£ππ€0.01 ππ π£0π + 0 = 0.01 ππ π£π + 3 ππ π£π
0.01 ππ π£0π = 3.01 ππ π£πAfter collision
β = 0.5 π β 0.5 π cos 40Β° = 0.1170 πππΈ0 + πΎπΈ0 = ππΈπ + πΎπΈπ
0 +1
23.01 ππ π£π
2 = 3.01 ππ 9.8π
π 2(0.1170 π) + 0
1.505 ππ π£π2 = 3.45 π½
π£π = 1.51 π/π
Combine
0.01 ππ π£0π = 3.01 ππ 1.51π
π π£0π = 455 π/π
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