Answer:
W = 1250 J = 1.25 KJ
Explanation:
The work done by the boy is due to the change in the position of the cement vertically. Hence, the work done in this case will be equal to the potential energy of the cement:

where,
W = Work done = ?
mg = W = weight of cement = 500 N
h = height covered = 2.5 m
Therefore,

<u>W = 1250 J = 1.25 KJ</u>
Answer:
the correct representation of the trough is b
The time when the two players will collide is 0.96 s.
The equation of motion of the two players is given as;
x1 = 0.1 m + (–3.9 m/s )t
x2 = –6.3 m + (2.8 m/s )t
The time when the two players collide, their displacement is equal or the difference in their position will be zero.

Thus, the time when the two players will collide is 0.96 s.
Learn more here: brainly.com/question/18033352
Answer:
The atom is mostly empty space.
Explanation:
Ernest Rutherford in the year 1911 developed a model of an atom. In his model the atom was shown that the atom is mostly empty spaces composed of negative electrons which orbits round a positive nucleus just like planets revolving round the sun.
Rutherford came up with this model by performing experiments in 1909 which involves the scattering of alpha particles on a thin gold foil. From this experiments he came up with his model.