Question

an object is thrown upward with kinetic energy 20joule if the object reaches maximum height of 4 metre calculate the mass of the object​

Answer 1

Answer:

Total energy(TE) = KE +PE

We will find the total energy at “the release point” and “the highest point” and equate them because this is what the “Law of conservation of energy” says.

Assumption: We assume the release point to act as the datum. We will find all PE with reference to that datum only. Also, Let Mass= m kg, g=10m/s2

TE at release point = KE+PE =20 + 0 = 20 J ………….(i)TE at highest point = KE + PE= 0+ 20m = 20m J………..(ii)

Here, Velocity = Zero. So, KE=0

and, Height = 2m. So, PE = mgh = m*10*2 J = 20m J

Equating the equations (i) and (ii) we get,

20m=20

so, m=1 Kg

hope it helped you....

Answer 2

Answer:

Total energy(TE) = KE +PE

Explanation:

We will find the total energy at “the release point” and “the highest point” and equate them because this is what the “Law of conservation of energy” says.

Assumption: We assume the release point to act as the datum. We will find all PE with reference to that datum only. Also, Let Mass= m kg, g=10m/s2

TE at release point = KE+PE =20 + 0 = 20 J ………….(i)

TE at highest point = KE + PE= 0+ 20m = 20m J………..(ii)

Here, Velocity = Zero. So, KE=0

and, Height = 2m. So, PE = mgh = m*10*2 J = 20m J

Equating the equations (i) and (ii) we get,

20m=20

so, m=1 Kg

So, Mass of the object = 1 Kg

Hope it helps!