A 4-kg bag of potatoes is held by a string. If the tension in the string is 39.2 N, (a) What is the state of motion of the bag? (b) What should the tension in the string be so that the bag...

A 4-kg bag of potatoes is held by a string. If the tension in the string is 39.2 N,

(a) What is the state of motion of the bag?

(b) What should the tension in the string be so that the bag accelerates upward at 1.8m/s2? (the S2 means s squared).

justaguide | College Teacher | (Level 2) Distinguished Educator

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A 4 kg bag of potatoes is held by a string. The tension in the string is equal to the force exerted on it by the bag of potatoes. Force is given by the product of mass and acceleration. As the tension in the string is 39.2 N, the bag of potatoes is being accelerated downwards at 39.2/4 = 9.8 m/s^2. This is equal to the acceleration due to the gravitational pull of the Earth. The bag is freely suspended in space by the string.

If the bag accelerates upwards at 1.8 m/s^2 the force to be exerted on it by the string is equal to (9.8 + 1.8)*4 = 46.4 N

There would be a tension of 46.4 N in the string if the bag is to be accelerated upwards at 1.8 m/s^2.