Answer:
Force of static friction between the two surfaces
Explanation:
When two surfaces come into contact, they exert a force that resist the sliding of the two surfaces. This force is called static friction.
This force is given by the relation

Where,
μ - coefficient of static friction
η - normal force acting on the body
When a force acts on a body placed on a rough surface, it doesn't do any work if the applied force was less than the force of static friction.
So, in order to move the body, the applied force should be greater than the force of static friction.
Answer:
D. It is easy to copy.
Explanation:
It is not B, or A, nor C.
The acceleration of the first block (4 kg) is -9.8 m/s².
The given parameters:
- <em>Mass of the first block, m₁ = 4.0 kg</em>
- <em>Mass of the second block, m₂ = 2.0 kg</em>
The net force on the system of the two blocks is calculated as follows;

where;
- <em>T </em><em>is the tension in the connecting string due weight of the first block</em>

Thus, the acceleration of the first block (4 kg) is -9.8 m/s².
Learn more about net force on two connected blocks here: brainly.com/question/13539944
1. What is the major function of the pons?
-Other than serving as a conduction pathway, the pons also contains a nucleus that is essential for breathing.
2. Why is the medulla the most vital part of the brain?
-Medulla is very important because it function for the involuntary movement and processes that happen in the body without giving a thought about it. It performs crucial tasks like regulating the blood pressure.
Answer:
The velocity of the skateboard is 0.774 m/s.
Explanation:
Given that,
The spring constant of the spring, k = 3086 N/m
The spring is stretched 18 cm or 0.18 m
Mass of the student, m = 100 kg
Potential energy of the spring, 
To find,
The velocity of the car.
Solution,
It is a case of conservation of energy. The total energy of the system remains conserved. So,






v = 0.774 m/s
So, the velocity of the skateboard is 0.774 m/s.