Question

A person of mass 50kg carrying a box walks up a staircase height and width of each step is 20 cm & 15 cm if the work done in walking 50 steps is 7840j the mass of the box is

Answer 1

Answer:

The answer is 30 Kg.

Explanation:

The box is brought to a height of =50×20 = 1000 cm = 10 m

Let the mass of the box is m.

So the total work done,

W = (50 + m) x g x h = = (50 +m) x 9.8 x 10

    = 98(50 +m)J

Now  98(50 +m) = 7840

   50 + m = 7840 / 98

   50 + m = 80

   m = 80 - 50

   m = 30 Kg

Thus the mass of the box is 30 Kg.

Answer 2

Explanation:

The box is brought to a height of =50×20=1000 cm=10 m=50×20=1000 cm=10 m

Let the mass of the box is m.

So the total work done,

W=(50+m)×g×h=(50+m)×9.8×10=98(50+m) JW=(50+m)×g×h=(50+m)×9.8×10=98(50+m) J

Now,

98(50+m)=7840

⇒50+m=80

⇒m=3098(50+m)=7840⇒

50+m=80

⇒m=30

Therefore mass of the box is 30 kg