1) A car initially traveling at 28.1 m/s undergoes a constant negative accelerat

Question

1) A car initially traveling at 28.1 m/s undergoes a constant negative acceleration of magnitude 1.40 m/s2 after its brakes are applied.

a)What is the angular speed of the wheels when the car has traveled half the total distance?

2)A uniform plank of length 4.9 m and weight 213 N rests horizontally on two supports, with 1.1 m of the plank hanging over the right support (see the drawing). To what distance x can a person who weighs 458 N walk on the overhanging part of the plank before it just begins to tip?

Explanation / Answer

1)Half stopping distance s = 99.46m

Linear speed at that point is
v = sqrt(u^2 + 2a*s)
v = sqrt(28.1^2 - 2*1.4*99.46) = sqrt(511.12) m/s
v = 22.60 m/s

Angular speed af wheels at that point is
? = v / r = 22.60m/s / r

Apply r value

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2)

(213/4.9m) = 43.46N per metre length.

(4.9 - 1.1) = 3.8m.between the supports.
Weight right of right support = (1.1 x 43.46) = 47.806N.
(47.806 x (1.1/2) = 26.29N/m. torque right.
Weight left of right support = (3.8 x 43.46) = 165.148N.
(165.148 x (3.8/2) = 313.78N/m. torque left.
L to R torque difference = (313.78

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