Physics
Mohan's father sells fruits and vegetables. Since Mohan has learnt about measuring mass at school, he is helping his father. He has a beam balance. Let us call the pans of the beam balance as A and B. There are known weights of 50 g, 200 g, 500 g and 1000 g at his shop.

How will Mohan weigh the following items? What will he place on pan A and pan B in each case?
(a) 1 kg of onions
(b) 250 g of ginger
(c) 750 g of apples
(d) 1 kg and 200 g of potatoes
(e) 50 g of chillies
Answer
To measure the mass of fruits and vegetables, each item is placed on one pan and standard weights are kept on the other pan of the beam balance. The weights are adjusted till the beam is horizontal and the pointer points vertically up. The sum of the masses of the standard weights gives the mass of the item placed.
(a) As,
1 kg = 1000 g
So,
He will put weight of 1000 g on pan A and 1 kg of onions on pan B.
(b) As,
250 g = 200 g + 50 g
Since, there is no weight present which has mass of 250 g so, he will use weights which are available i.e., one weight of 200 g and one of 50 g.
Hence, he will put one weight of 200 g and one of 50 g on pan A and 250 g of ginger on pan B.
(c) As,
750 g = 500 g + 200 g + 50 g
Since, there is no weight present which has mass of 750 g so, he will use weights which are available i.e., one weight of 500 g, one with value of 200 g and one of 50 g.
Hence, he will put one weight of 500 g, one of 200 g and one of 50 g on pan A and 750 g of apples on pan B.
(d) As,
1 kg and 200 g = 1 kg + 200 g = 1000 g + 200 g
So, he will put one weight of 1000 g and one of 200 g on pan A and 1 kg and 200 g of potatoes on pan B.
(e) Now, he will put one weight of 50 g on pan A and 50 g of chillies on pan B.
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