Answer:
Time, t = 80 seconds
Explanation:
Given that,
The frequency of the oscillating mass, f = 1.25 Hz
Number of oscillations, n = 100
We need to find the time in which it makes 100 oscillations. We know that the frequency of an object is number of oscillations per unit time. It is given by :



t = 80 seconds
So, it will make 100 oscillations in 80 seconds. Hence, this is the required solution.
Answer: The area of brick in contact with the floor is 1539
.
Explanation:
Given: Length = 19 cm
Width = 9 cm
Height = 9 cm
As the brick is rectangular in shape. Hence, its area will be calculated as follows.

Substitute the values into above formula as follows.

Thus, we can conclude that area of brick in contact with the floor is 1539
.
Answer:
B. Attract each other with a force of 10 newtons.
Explanation:
Statement is incorrectly written. <em>The correct form is: A </em>
<em> charge and a </em>
<em> at a distance of 0.3 meters. </em>
The two particles have charges opposite to each other, so they attract each other due to electrostatic force, described by Coulomb's Law, whose formula is described below:
(1)
Where:
- Electrostatic force, in newtons.
- Electrostatic constant, in newton-square meters per square coulomb.
- Magnitudes of electric charges, in coulombs.
- Distance between charges, in meters.
If we know that
,
and
, then the magnitude of the electrostatic force is:


In consequence, correct answer is B.