To find the mass of the object, we use Newton's Second Law:

$F = ma$

where:

• $F$ is the force applied (21.0 N),
• $m$ is the mass of the object (unknown),
• $a$ is the acceleration of the object.

Step 1: Calculate the acceleration

Acceleration ($a$) is the change in velocity over time:

$a = \frac{\Delta v}{\Delta t}$

Given:

• Initial velocity ($v_i$) = 13.2 m/s
• Final velocity ($v_f$) = 15.1 m/s
• Time ($\Delta t$) = 8.0 seconds

$a = \frac{15.1 \text{ m/s} - 13.2 \text{ m/s}}{8.0 \text{ s}}$

$a = \frac{1.9 \text{ m/s}}{8.0 \text{ s}} = 0.2375 \text{ m/s}^2$

Step 2: Solve for mass using Newton's Second Law

Rearrange the formula $F = ma$ to solve for $m$:

$m = \frac{F}{a}$

$m = \frac{21.0 \text{ N}}{0.2375 \text{ m/s}^2}$

$m \approx 88.42 \text{ kg}$

The closest option is D. 88 kg.

Final Answer:

D. 88 kg

Would you like any further details or have any questions?

Here are some related questions:

1. How does Newton's Second Law relate to real-life scenarios?
2. What happens to the mass calculation if the force were doubled?
3. What units should be used when calculating acceleration?
4. How do changes in time affect acceleration?
5. Can the mass be determined if only the force and velocity are known?

Tip: Always check units to ensure consistency when applying formulas in physics problems.