1.) A bird with a mass m = .2 kg is sitting in the middle of a clothes line whic
ID: 1522723 • Letter: 1
Question
1.) A bird with a mass m = .2 kg is sitting in the middle of a clothes line which makes a smale angle 0= 5.7 degrees with horizontal. Find the magnitude of the tension in the string.
Answer should be 10.
2.) a locomotive applied a force F = 40,000 N to a loaded platform with M = 16,000 which in turn is connected to an empty platoform with m = 4000 kg, FInd the force T in (kN) which is applied to the empty platform.
answer should be 0
answer should be 8
3.) assume that the stairs in Tiernan Hall Make an angle of 30 degrees with horizontal. How fast in (m/s) should M = 76 kg run upstairs to deliver a power of 746 watts.
answer should be 2
4.) A certain particle with mass M = 2kg can move in the x-y plane. The particle starts at the origin with speed v0= 4.25 m/s and after some time is located at r = 4i - 3j. A constant force F = 4i + 3j acts on the particle. FInd the particle speed in m/s at the final point given b r.
Explanation / Answer
1) Let the tension be T
Balancing force in vertical
2T sin 5.7 degree = mg
0.1986 T = 0.2*9.8
T = 0.2*9.8/0.1986 = 9.87 N
2) since the masses are connected, their acceleration is same. Let tension be T
(40000 N - T)/16000 kg = T/4000 kg
40000 - T = 4T
T = 8000 N = 8 kN
3) Power = F.v
746=76*9.8*v*sin 30 degree
v = 746/(76*9.8*0.5) = 2 m/s
4) Work done = change in KE
F.r = 0.5*2(v^2- 4.25^2)
4*4 -3*3 = v^2- 4.25^2
7 = v^2 - 18.0625
v = sqrt (7+18.0625)
= 5 m/s
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