please help with detailed explanation. Thank you 4) Two blocks are connected by

Question

please help with detailed explanation. Thank you

4) Two blocks are connected by a string that goes over an ideal pulley as shown in the figure. Block A has a mass of 3.00 kg and can slide over a rough plane inclined 30.0° to the horizontal. The coefficient of kinetic friction between block A and the plane is 0.350. Block B has a mass of 4.00 kg. A) What is the acceleration of the blocks? B) If block B is released from 2 m above the ground, how long it will take to hit the ground? C) Find the ideal mass of block B if the static frictional coefficient between block A and plane is 0.4. 120 pts] 30.0°

Explanation / Answer

for B

mB*g - T = mB*a ............(1)

for A

T - mA*g*sintheta - uk*mA*g*costheta = mA*a ......(2)

1 + 2

mB*g - mB*a - mA*g*sintheta - uk*mA*g*costheta = (mA+mB)*a

1 + 2

mB*g - mA*g*sintheta - uk*mA*g*costheta = (mA+mB)*a

4*9.8 - 3*9.8*sin30 - 0.35*3*9.8*cos30 = (3+4)*a

acceleration a = 2.22 m/s^2

-------------------

B)

y = voy*t + (1/2)*a*t^2

-2 = 0 - (1/2)*2.22*t^2

t = 1.34 s

C)

T = mB*g

for A

Fnet = 0

T - mA*g*sintheta - us*mB*g*cos30 = 0

mB*g - mA*g*sintheta - us*mB*g*cos30 = 0

mB*9.8 - 3*9.8*sin30 - 0.4*3*9.8*cos30 = 0

mB = 2.54 kg

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