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course Phy 201
(1/2) * (3/4)= 3/8 #####$&*
(12/5) * (25 / 21) = 180/315 = 4/7 ####
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(4/3) * 3 = 12/3 = 4 ####
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(5/8) * 16 = 80/8 = 10 ####
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(5/9) / (3/4) = 20/27 #####
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(13/25) / 2 = 13/50 ######
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12 / (2/3)= 36/2 = 18 #######
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(4 / 3^2) * 3= 4/9 * 3/1 = 12/9= 4/3 #######
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(a/b) * (c/d)= ac/bd ######
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(a/b) / (c/d)= ad/bc #######
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(a/b) * c= ac/b ######
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a / (b / c)= ac/b ######
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(a/b) / c = a/bc ######
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(a / b) / b = a/b2 #######
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(a / b^2) * b = ab/b2 #######
@& This reduces.*@
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(a / b^2) / b =ab/b2 #######
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Now do the following calculations:
(m / s) * s= m ######
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kg * (m / s^2) = kgm/s2 ######
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(m/s^2) * s = ms/s2 #######
@& Good, but reduce.*@
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(m/s^2) * m = m2/s2 ########
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(kg * m / s^2) / (m / s) = kg*m*s/s2*m= kgs/s2 #######
@& Very good, but one more reduction step gives you kg / s.*@
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5 m * (1 km / (1000 m) )= 5,000 m #########
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80 ft * (31 cm / ft)= 2,480 cm ########
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20 dollars * (100 cents / dollar) = 2,000 cents ######
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12 pounds * (9.8 Newtons / (2.2 pounds) )= 118.8/2.2 = 54 newtons #####
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Now answer the following:
Work out and show units in every step:
If F = m a, then if m = 5 kg and a = 3 m/s^2, what is the value of F?
F= ma
F= 5 kg* 3m/s2
F= 15 kgm/s2 #######
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If F = m a and F = 15 pounds when a = 5 feet / second^2, then what is m?
15lbs.* 5 ft./s2 = 5 ft./ss (m)/5 ft./ s2
75 lbs.(ft/s2)/(ft.)= 75lbs.(ft.) = 1 = 75lbs. = s2= 75.lbs.
s2 ft. s2
75 lbs. = ___________kg= 160 kg #####
2.2046 lbs.
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@& Your calculation 15lbs.* 5 ft./s2 would correspond to F * a. The formula doesn't involve multiplying F by a. To get m you would divide F by a.
Still, you have a lot of good steps here.*@
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If KE = 1/2 m v^2 with m = 2 kg and v = 4 m/s, then what is KE?
KE= ½ * 2kg * 4m/s2= 4kg m/s2 ########
@& When v is squared, the entire quantity 4 m/s is squared, giving you 16 m^2 / s^2.*@
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If F = k Q q / r^2 with k = 9 GigaNewton m^2 / C^2, Q = 2 C and q = 3 C with r = 10 m, then what is F?
F= 9 m2/s2 * 2c* 3c/ 10 m2=
F= 54m2 c2/c2 * 1/10 m2
F=540
@& You left out the GigaNewtons in every step. Otherwise good.*@
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Self-critique (if necessary):
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Self-critique rating:
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@& It looks like you went to the trouble of making the exponents look like exponents. However that's extra work for you, and it doesn't come through the text form. Must easier to use the ^ for exponentiation.*@
@& You are using units at every step, and are doing very well with this. You have a couple of errors, but you'll understand my notes. You're in very good shape on this, and then you shouldn't have any trouble with units throughout the course.*@