A girl lifts her 30-kg (294 N) knapsack a vertical distance of 0.50 m and then she carries it 10 m across the park to the water fountain. How much work is done by the girl?

Please help me.

Why did the girl bring her knapsack to the water fountain? Because it was thirsty and wanted some hydration! Ah, the mysteries of life. Anyway, let's get back to your question.

To calculate the work done by the girl, we need to consider two things: lifting the knapsack vertically and carrying it horizontally.

When the girl lifts the knapsack vertically, she does work against the force of gravity. The work done is given by:

Work = Force x Distance

In this case, the force is the weight of the knapsack (294 N) and the distance is the vertical distance it was lifted (0.50 m). So, the work done in lifting the knapsack is:

Work = 294 N x 0.50 m

Now, when the girl carries the knapsack horizontally, no vertical displacement occurs. So, the work done in carrying the knapsack is simply the force of gravity multiplied by the distance traveled horizontally:

Work = Force x Distance

In this case, the force is still the weight of the knapsack (294 N) and the distance is the horizontal distance traveled (10 m). So, the work done in carrying the knapsack is:

Work = 294 N x 10 m

Now all you have to do is add the two values together to find the total work done by the girl. Just be careful not to trip on any punchlines along the way!

To find the work done by the girl, we can use the formula:

Work = Force × Distance × cos(θ)

where:
- Force is the applied force on the object,
- Distance is the displacement of the object, and
- θ (theta) is the angle between the force vector and the displacement vector.

In this case, the girl exerts a force to lift and carry the knapsack. The force she exerts is equal to the weight of the knapsack, which is given as 294 N. The displacement of the knapsack in the vertical direction is 0.50 m, and in the horizontal direction is 10 m.

Let's calculate the work done by the girl:

Work = Force × Distance × cos(θ)
= 294 N × (0.50 m + 10 m) × cos(0°)
= 294 N × 10.50 m × cos(0°)

Since cos(0°) is equal to 1, the equation simplifies to:

Work = 294 N × 10.50 m × 1
= 3087 N·m

Therefore, the girl does 3087 N·m (or Joules) of work to lift and carry the knapsack.