Two objects are connected by a massless string that passes over a massless, fric
ID: 1618379 • Letter: T
Question
Two objects are connected by a massless string that passes over a massless, frictionless pulley. The pulley hangs from the ceiling. The mass of the heavier object is 15 kg. The objects move starting from rest, and after 3 second the velocity of the lighter mass increases to 4 m/s up. The weight of the 15 kg object is 15 kg 15 kg (-y) -147 N (y) -147 N (-y) 147 kg (-y) The acceleration of the 15 kg object is 1.33 m/s^2 (-y) 1.33 m/s^2 (+y) 4.00 m/s^2 (-y) 4.00 m/s^2 (+y) 9.81 m/s^2 (-y) The magnitude of the tension in the rope is 19.95 N 60.0 N 87.0 N 127 N 147 N The mass of the lighter object is 4.99 kg 6.12 kg 7.81 kg 8.88 kg 11.4 kg The support (ceiling) force is 120 N 174 N 254 N 259 N 294 N.Explanation / Answer
i) Weight of 15 kg object is 15g(-y)=147(-y)
ii) For acceleration of 15 kg object=
v=u+at
4=0+a*3
a=(4/3)(-y) as heavier mass will have an acceleration in downward direction
iii) Tension in rope=15g - 15a=147-15*4/3=127N
iv) mass of lighter object can be calculated as
T-mg=ma
m=T/(g+a)=127/(9.8+1.33)=11.4 kg
v) Support force=2*tension=2*127*254N