When pulling one end of a spring balance while holding the other with my other end the reading is 10 kg. What is the total force applied? Does an equal force need to be applied by both my hands according to Newton's third law. Please explain.

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When you catch one end of a spring balance in one hand and pull the other end to show a reading of 10 kg, the force applied by your hand that is pulling at the end is 10*9.8 = 98N.

The hand with which you hold the spring balance also needs to apply to a force though it may not be equal to 98 N, but slightly less due to the weight of your hand itself and and the weight of the spring balance.

If there was no force applied by your other hand you could lift the spring balance by applying a force equal to just the product of mass of the spring balance and the acceleration due to gravity. Also, the reading shown on the spring balance would be 0 kg instead of 10 kg.

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