At a given instant in time, a 10-kg rock is observed to be falling with an acceleration of 7.0 m/s2. What is the magnitude of the force of air resistance acting upon the rock at this instant?

-70n

To find the magnitude of the force of air resistance acting upon the rock, we need to use Newton's second law of motion, which states that the net force acting on an object is equal to the product of its mass and its acceleration.

Here's how to calculate the magnitude of the force of air resistance:

Step 1: Write down the given values:
- Mass of the rock (m) = 10 kg
- Acceleration of the rock (a) = 7.0 m/s^2

Step 2: Recall Newton's second law of motion:
- Force (F) = mass (m) x acceleration (a)

Step 3: Substitute the given values into the formula:
- Force (F) = 10 kg x 7.0 m/s^2

Step 4: Calculate the force:
- Force (F) = 70 N

So, the magnitude of the force of air resistance acting upon the rock at this instant is 70 Newtons (N).

To determine the magnitude of the force of air resistance acting upon the rock, we can use Newton's second law of motion, which states that the net force is equal to the mass of the object multiplied by its acceleration.

The net force acting on the rock is given by the equation:

Net force = mass x acceleration

In this case, the mass of the rock is 10 kg and the acceleration is 7.0 m/s^2. Substituting these values into the equation, we have:

Net force = 10 kg x 7.0 m/s^2

Simplifying the equation, we find that the net force acting on the rock is 70 N.

However, we know that the force of air resistance acts in the opposite direction to the motion of the object, so it is a negative force. Therefore, the magnitude of the force of air resistance is the absolute value of the net force, which in this case is 70 N.

So, the magnitude of the force of air resistance acting upon the rock at this instant is 70 N.