- #1
Elphaba
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An 80 kg person standing on a 20 kg plateform is suspended by a rope passing over a stationary pulley that is free to rotate. The other end of the rope is held by the person. The masses of the rope and pulley are negligible. You may use g=10 m/s/s. Assume that friction is negligible and the parts of the rope shown remain verticle.
ok.. so the whole system is 100kg = 1000N right?
(a) if the platform and the person are at rest, what is the tension in the rope?
T=NetForce-Mg (i think)
so mg = 1000N
and NF= 1000N too??
The person now pulls on the rope so that the acceleration of the person and the platform is 2m/s/s upward.
(b) What is the tension in the rope under these new conditions?
would NF change?
(c) Under these new conditions, what is the force exerted by the platform on the person?
F= ma
so... platform on person... 20kg on 80 kg.. accel is 2...
um... confused...what do i do now?
After a short time, the person and the platform reach and sustain and upward velocity of 0.4m/s
(d) Determine the power output of the person required to sustain the velocity.
Hm... he hasn't taught us power yet... A little help please?
ok.. so the whole system is 100kg = 1000N right?
(a) if the platform and the person are at rest, what is the tension in the rope?
T=NetForce-Mg (i think)
so mg = 1000N
and NF= 1000N too??
The person now pulls on the rope so that the acceleration of the person and the platform is 2m/s/s upward.
(b) What is the tension in the rope under these new conditions?
would NF change?
(c) Under these new conditions, what is the force exerted by the platform on the person?
F= ma
so... platform on person... 20kg on 80 kg.. accel is 2...
um... confused...what do i do now?
After a short time, the person and the platform reach and sustain and upward velocity of 0.4m/s
(d) Determine the power output of the person required to sustain the velocity.
Hm... he hasn't taught us power yet... A little help please?