Answer: Work done by the box will be 8 Joules.
Explanation:
Work done by a substance is the product of the force applied on it and the displacement of a substance.
Mathematically,

Where,
W = work done = ? J
F = Force applied = 4 N
s = displacement = 2 m
Putting values in above equation, we get:

Hence, work done by the box will be 8 Joules.
The force of friction is equal to the pushing force, and the acceleration is zero
Explanation:
In this problem, we are pushing a piano along the floor, in the horizontal direction.
There are 2 forces acting in the horizontal direction on the piano:
- The applied force,
, acting forward - The force of friction,
, acting backward
Therefore, the net force in the horizontal direction is

According to Newton's second law, the net force is equal to the product between the piano's mass (m) and its acceleration:

Combining the two equations,

However, we are also told that the piano moves at constant speed, therefore the acceleration is zero:

And so,

which means that the force of friction is equal to the applied force.
Learn more about Newton's second law:
brainly.com/question/3820012
#LearnwithBrainly
<h2>Right answer: a number and a unit</h2>
The measurement consists in <em>comparing a selected pattern with the object or phenomenon whose physical magnitude is going to be measured, to find out how many times the pattern is contained in that magnitude.</em> That is, it is about identifying or quantifying a particular characteristic or aspect of a particular object or construct.
Now, a well done measurement has two parts:
-The number gives us information about the quantity of the measurement, or in other words, the magnitude of the measurement and its precision.
-The units gives us information about the property that is being measured. This is quite important, because a measurement or result with no units is useless.
Note the units may be expressed with letter or symbols, depending on what we are measuring.
Answer:
a = 1.666... m/s²
Explanation:
a = v2 - v1 / t2 - t1
a = 21m/s - 14m/s / 6s - 0s
a = 7m/s / 6s
a = 1.666... m/s²
The height of the rail on top of the press box where the ball was dropped from is 11.025 m.
The given parameters:
- Time of motion of the ball, t = 1.5 s
- Let the height of the rail = h
<h3>Maximum height of fall;</h3>
- The maximum height through which the ball was dropped from is calculated by applying second equation of motion;

Thus, the height of the rail on top of the press box where the ball was dropped from is 11.025 m.
Learn more about height of projectiles here: brainly.com/question/10008919