Answer:
a.
b. 
Explanation:
<u>Given:</u>
- Velocity of the particle, v(t) = 3 cos(mt) = 3 cos (0.5t) .
<h2>
(a):</h2>
The acceleration of the particle at a time is defined as the rate of change of velocity of the particle at that time.

At time t = 3 seconds,

<u>Note</u>:<em> The arguments of the sine is calculated in unit of radian and not in degree.</em>
<h2>
(b):</h2>
The velocity of the particle at some is defined as the rate of change of the position of the particle.

For the time interval of 2 seconds,

The term of the left is the displacement of the particle in time interval of 2 seconds, therefore,

It is the displacement of the particle in 2 seconds.
Answer;
The above statement is true.
-A photograph is taken by letting light fall on a light-sensitive medium, which then records the image onto that medium.
Explanation;
-A photograph is created when light is allowed to fall on a light-sensitive medium. The pattern of light creates an image that is recorded by the photographic device. How light or dark a photograph is depends on how much light was allowed to fall on the light-sensitive medium.
-A camera is a light-tight box that contains a light-sensitive material or device and a way of letting in a desired amount of light at particular times to create an image on the light-sensitive material.
Answer:
7 meters, 2.8 meters
Explanation:
work done (nm) = force (n) * distance (m)
140= 20 * m
140/20 = m
m=7 meters
140= 50 * m
140/50 = m
m= 2.8 meters
They do the method 3 times to be sure. Because if you do it once, that could mean anything. If you do it twice, it may or may not have the same result. If you do it 3 times and it matches one of the previous answers, then it's likely that it's correct.