A crane is lifting a crate mass 600kg vertically.

i)If the crate is travelling at a constant speed, find the tension in the lifting cable.

ii)If instead the crate is accelerating upwards at 0.02m/s, find the tension in the lifting cable.

Cheers

Printable View

- May 7th 2008, 01:18 PMhelpishereTension Question
A crane is lifting a crate mass 600kg vertically.

i)If the crate is travelling at a constant speed, find the tension in the lifting cable.

ii)If instead the crate is accelerating upwards at 0.02m/s, find the tension in the lifting cable.

Cheers - May 7th 2008, 01:25 PMDanshader
part i)

when the mass is moving a t a constant speed the acceleration of the mass is 0 ms^-1.

Using newton's second law of motion:

resultant force, F = ma

F = T - mg

where T = tension in the cable

T - mg = ma →(1)

but a = 0

T - mg = 0

T = mg

T = 600(9.81)

T = 5886 N

part ii)

given now that the mass accelerates upwards with an acceleration of 0.02 ms^-1. To achieve this the tension in the cable must be larger than the weight of the mass

from (1)

T - mg = ma

T = m(a+g)

T = 600(0.02+9.81)

T = 5898 N