Question

A block of mass m is placed on a weighing machine and it is also attached to a spring balance. The whole system is placed in a lift as shown in figure. Lift is moving with constant acceleration 10m/s2 in upward direction. The reading of the weighing machine is 500N and the reading of spring balance is 300N. Find the actual mass of the block in kg. Take g=10m/s2.

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Answer 1

Answer:

• 40 kg

Explanation:

Given:

• A block of mass m is placed on a weighing machine and it is also attached to a spring balance.
• The whole system is placed in a lift
• Lift is moving with constant acceleration 10m/s² in upward direction
• The reading of the weighing machine is 500N
• The reading of spring balance is 300N

To Find:

• Mass of the block (in kg)

Solution:

• 'm' be the mass of block
• Let us apply Newton's law on the block (vertical direction)

T + N - mg = ma _______①

• T = 300N
• N = 500N
• a = 10m/s²

⇒ m = T+N / g+a

⇒ m = 500+300 / 20 kg

⇒ m = 800/20 kg

⇒ m = 40 kg

∴ Mass of the block is 40 kg