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a) A10 kg block is hanging from a rope. Find the (magnitude of the) tension in t

ID: 1793814 • Letter: A

Question

a) A10 kg block is hanging from a rope. Find the (magnitude of the) tension in the rope when i) the block is stationary. ii) the block is moving upward with a steady speed of 5.0 m/s. iii) the block is accelerating upward with a steady acceleration of 5.0 m/s2 b) A 1100 kg car, whose wheels are locked, is being dragged across the pavement by a cable held at an angle of 20° above the horizontal. The coefficient of kinetic friction between the car and the ground is .= 0.80. The car starts from rest, and after 3.0 s is moving at a speed of 1.5 m/s. 120° What is the (magnitude of the) tension in the cable T?

Explanation / Answer

a) fnet = m

T - m g = 0

T = 10 x 9.8 = 98 N  


(ii) moving with constant velocity, a = 0

so Fnet = 0

T = m g = 98 N  

(iii) T - m g = m a

T = 10 (9.8 + 5) = 148 N  

b) vf = vi + a t

1.5 = 0 + 3 a = > a = 0.5 m/s^2


in vertical, T sin20 + N - m g = 0

N = m g - T sin20


in horizontal, Tcos20 - f = m a

T cos20 - 0.80 m g + 0.80 T sin20 = 1100 x 0.5

T = 7561 N