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kenny6666 [7]
3 years ago
5

You testify as an "expert witness" in a case involving an accident in which car A slid into the rear of car B, which was stopped

at a red light along a road headed down a hill. You find that the slope of the hill is θ = 12.0°, that the cars were separated by distance d = 25.0 m when the driver of car A put the car into a slide (it lacked any automatic anti-brake-lock system), and that the speed of car A at the onset of braking was v0 = 18.0 m/s.
(a) With what speed did car A hit car B if the coefficient of kinetic friction was 0.60 (dry road surface)?
____ m/s

(b) What was the speed if the coefficient of kinetic friction was 0.10 (road surface covered with wet leaves)?
____ m/s
Physics
1 answer:
natulia [17]3 years ago
3 0

F=mgsinα –F(fr)=

= mgsinα - μmgcosα

a=F/m =g(sinα – μcosα)

=9.8(sin14-0.57•cos14)= -3.04 m/s²

v²=v₀²+2ad

v=sqrt{ v₀²+2ad} =

=sqrt{18²+2• (-3.04) •25}=13.1 m/

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Answer:

option (a)

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6 0
3 years ago
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posledela
The correct choice is C .

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An aluminum bar 600mm long, with diameter 40mm, has a hole drilled in the center of the bar. The hole is 40mm in diameter and 10
s2008m [1.1K]

Answer:

<em>1.228 x </em>10^{-6}<em> mm </em>

<em></em>

Explanation:

diameter of aluminium bar D = 40 mm  

diameter of hole d = 30 mm

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modulus of elasticity E = 85 GN/m^2  = 85 x 10^{9} Pa

length of bar L = 600 mm

length of hole = 100 mm

true length of bar = 600 - 100 = 500 mm

area of the bar A = \frac{\pi D^{2} }{4} =  \frac{3.142* 40^{2} }{4} = 1256.8 mm^2

area of hole a = \frac{\pi(D^{2} - d^{2}) }{4} = \frac{3.142*(40^{2} - 30^{2})}{4} = 549.85 mm^2

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