A bucket of water weighing 6 kg is being dragged straight up by a string at a constant speed.

What is the rope’s tension?

1. Approximately 42 N

2. Approximately 60 N

3. Approximately 78 N

4. Since the bucket has no acceleration, its acceleration is zero.

The bucket’s speed changes at a certain point. The bucket now has a constant upward acceleration of 3 m/s^2. How tight is the rope now?

1. about 42 N

2. about 60 N

3. about 78 N

4. It is increasing as the speed increases.

Now assume that the bucket has a downward acceleration, with a constant acceleration of magnitude 3 m/s^2.

How much tension is there in the rope?

1. about 42 N

2. about 60 N

3. about 78 N

4. With increasing speed, it decreases.

Table of Contents

### 1 Answer

Gravitational acceleration is equal to 9.8 m/s^2. For simplicity, many physics problems assume a value of 10. This is the acceleration of any object on Earth whose velocity is not changing.

A. On earth, under the influence of earth gravity (9.8 m/s*2), the answer is 2) 60 N (6kg x 9.8m/s*2 = 60 N). In space, the answer is 4) 0 N because there is no acceleration.

B. As the velocity increases against gravity, you must add gravity (9.8 m/s*2) and acceleration (3 m/s*2) to get the total acceleration. All four answers are incorrect in space. Therefore, this problem assumes earth gravity.

C. The bucket seems to still be on the ground since it is being lowered. Currently, the tension is 1) about 42 N due to the earth’s gravity (9.8m/s*2) being offset by the accelerated lowering (3m/s*2), resulting in a net acceleration of 6.8m/s^2. 42 N is obtained by multiplying this number by 6Kg.

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