<span>Unexpected orbital velocities of stars around the centers of galaxies led astronomers to predict the existence of dark matter. Dark matters are hypothetical substance that are believed to account for around five-sixths of the matter in the universe.</span>
Answer:
a) 2.53 * 10^-2 m/s
b) -4.78 * 10^-2 m/s
c) 1.21 * 10^-1 m/s
Explanation:
Given data :
Mass of block = 10 kg
Measuring 250mm on each side
a) calculate the speed when a force of 75N is applied to pull block upwards
F = f + W sin∅ ( equation for applying the force of equilibrium condition in the x axis ) ----- ( 1 )
f ( friction force )= ( 16400v * 6.25 *10^-2) = 1025 v
F ( force applied ) = 75
W ( weight of block ) = 10 * 9.81 = 98.1 N
∅ = 30°
input values into equation 1
V =
= 2.53 * 10^-2 m/s
b) Speed when no force is applied on the block
F = f + W sin∅
F = 0
f = 1025 V
W = 98.1 N
∅ = 30°
hence V =
= - 4.78 * 10^-2 m/s
c) when a force is applied to push block down the incline
F = f + W sin∅ ----- ( 3 )
F = 75 N
f = 1025 V
W = 98.1 N
∅ = 30°
input values into equation 3 considering the fact that the weight of the block is acting in the opposite direction
75 = 1025 V - 98.1 ( sin 30° )
V =
= 1.21 * 10^-1 m/s
Answer:
Explanation:
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Answer is C.