The speed of the brick dropped by the builder as it hits the ground is 17.32m/s.
Given the data in the question;
Since the brick was initially at rest before it was dropped,
- Initial Velocity;

- Height from which it has dropped;

- Gravitational field strength;

Final speed of brick as it hits the ground; 
<h3>Velocity</h3>
velocity is simply the same as the speed at which a particle or object moves. It is the rate of change of position of an object or particle with respect to time. As expressed in the Third Equation of Motion:

Where v is final velocity, u is initial velocity, h is its height or distance from ground and g is gravitational field strength.
To determine the speed of the brick as it hits the ground, we substitute our giving values into the expression above.

Therefore, the speed of the brick dropped by the builder as it hits the ground is 17.32m/s.
Learn more about equations of motion: brainly.com/question/18486505
Answer: D. 1,2,3
The paper pots used
in steamboat restaurants will not catch fire when in contact with the flame for
the heat is conducted quickly to the water because the paper is thin and the burning
temperature of the paper is much higher than the boiling point of water. Lastly, the texture of the paper is thick that it can withstand the temperature of the flame.
The correct formula to use for the situation given above is: F = MA, where F is the applied force, M is the mass of the object and A is the acceleration.
From the details given in the question, we are told that:
F = 18, 400N
M = 145 g = 145 / 1000 = 0.145 kg
A = ?
From the equation F = MA
A = F / M
A = 18,400 / 0.145 = 126,896.55 = 1.27 *10^5.
Therefore, the correct option is C.