Two people carry a small but heavy electric motor by placing it on a light board

Question

Two people carry a small but heavy electric motor by placing it on a light board 3.00 m long. One person lifts at one end with a force oS N, and the other lifts at one with FORCE OF 400 n, and the opposite end with a force of 600 N. (a) What is the weight of the motor, and where along the board is it located? (b) Suppose the board is not light but weighs 200 N, and the two people each exert the same forces as before. What is the weight of the motor in this case, and where is it located along the board?

Explanation / Answer

According to the given problem,

a) Using torques to find the center of mass of the motor

the weight of the motor = 400 +600 = 1000 N

let's sum torques around the end with the 400N (I will call this the left end)

torque = force x perpendicular distance

since the forces are weights that are perpendicular to the board, we want the distance from the left end

torque due to motor = 1000x where x is its distance from the left end

torque due to 600N force = 600*3

therefore we have 1000x = 1800 => x=1.8 m from the left end

b) Now we have to consider the torque due to the weight of the board, this will act at the midpoint of the board or 1.5 meter from the left end.

the weight of the motor in this case = 400 + 600 - 200 = 800 N

torque due to weight of board = 200 x 1.5 = 300

torque due to motor = 800x

torque due to 600N force = 600x3=1800

so we have

300+800x=1800

800x = 1500 => x= 1.875 m

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.