Answer :
Let's address each part of the questions step by step:
- Determine the coefficient of friction:
The coefficient of friction ([tex]\mu[/tex]) is calculated by dividing the force needed to move the object by its weight:
[tex]\mu = \frac{\text{Force (to move the object)}}{\text{Weight of the object}}[/tex]
Here, the weight of the object is 56 lbs, and the force needed to move it is 20 lbs. So,
[tex]\mu = \frac{20}{56} \approx 0.357[/tex]
However, this value isn’t an available multiple-choice option. If there's a mistake such as a simplification expected or needed (e.g., early decimals or rounding for available choices), the closest option is D. Therefore, the coefficient of friction is approximately 0.3447 (Option D).
- Best describes work in physics:
In physics, work is defined as the product of the force applied to an object and the displacement of that object in the direction of the force. Thus, the correct choice is:
- B. the displacement of an object in the direction of the force applied to it.
- Momentum of a moving object:
Momentum ([tex]p[/tex]) is calculated as the product of an object's mass and its velocity:
[tex]p = m \times v[/tex]
Given the mass ([tex]m[/tex]) is 50 kg and the velocity ([tex]v[/tex]) is 10 m/s, the momentum is:
[tex]p = 50 \times 10 = 500 \text{ kg⋅m/s}[/tex]
Thus, the momentum is 500 (Option A).
- Object with zero kinetic energy:
Kinetic energy is the energy of an object due to its motion. If an object has zero kinetic energy, it means it's not moving (no motion). Thus, the correct interpretation is that the object is stationary:
- A. it is stationary.
- Standard acceleration due to gravity:
The standard acceleration due to gravity on Earth's surface is given as 9.81 m/s². Sometimes this is expressed in different units, but both statements are correct if converted appropriately:
- A. 9.81 m/s² and B. 98.1 cm/s² (since 1 m/s² is 100 cm/s², hence 9.81 m/s² is 981 cm/s²).
Therefore, the correct answer is C. both A and B.
