john is using a pulley to lift the sail on his sailboat. the sail weighs 150N and he must lift it at 4.0m. how much work must be
1 answer:
The work done on the sail is 600 J
Explanation:
The work done to lift the sail is equal to the gain in gravitational potential energy of the sail, therefore is:
where
m is the mass of the sail
g is the acceleration of gravity
(mg) is the weight of the sail
is the change in height of the sail
In this problem we have
mg = 150 N (weight)
Substituting, we find the work done:
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Answer:
F = 2123.33N
Explanation:
In order to calculate the torque applied by the left support, you take into account that the system is at equilibrium. Then, the resultant of the implied torques are zero.
Next, you calculate the resultant of the torques around the right support, by taking into account that the torques are generated by the center of mass of the wooden, the person and the left support. Furthermore, you take into account that torques in a clockwise direction are negative and in counterclockwise are positive.
Then, you obtain the following formula:
(1)
τl: torque produced by the left support
τp: torque produced by the person
τcm: torque produced by the center of mass of the wooden
The torque is given by:
(2)
F: force applied
d: distance to the pivot of the torque, in this case, distance to the right support.
You replace the equation (2) into the equation (1) and take into account that the force applied by the person and the center of mass of the wood are the their weight:
Where d1, d2 and d3 are distance to the right support.
You solve the equation for F and replace the values of the other parameters:
The force applied by the left support is 2123.33 N