Measurement — Important Questions

-0.05 cm

Step 1: When the zero of the Vernier scale is to the RIGHT of the main scale zero, it is a POSITIVE zero error. Step 2: Positive zero error = +n × LC = +5 × 0.01 = +0.05 cm. Step 3: Zero correction is always opposite in sign to zero error. Step 4: Since zero error is +0.05 cm, zero correction = -0.05 cm. Step 5: This means the reading is more than actual, so we subtract the correction from the reading.

0.01 mm

Step 1: Least count of screw gauge = Pitch / Total number of head scale divisions. Step 2: Pitch = 1 mm, Head scale divisions = 100. Step 3: LC = 1 mm / 100 = 0.01 mm. Step 4: This means the screw gauge can measure up to 1/100th of a millimetre. Step 5: This is 10 times more precise than a Vernier caliper (which has LC = 0.1 mm).

Spring balance

Step 1: Hooke's law states that the extension of a spring is directly proportional to the force applied to it. Step 2: A spring balance uses this principle — when an object is hung, the spring stretches proportionally to the weight. Step 3: A pointer on the rod reads the weight on a graduated scale. Step 4: A physical balance or beam balance compares mass with standard masses — it does NOT use Hooke's law. Step 5: Spring balance measures weight (in Newtons), not mass.

588 N

Step 1: Weight = mass × acceleration due to gravity, i.e., W = mg. Step 2: Given mass (m) = 60 kg and g = 9.8 m/s². Step 3: W = 60 × 9.8 = 588 N. Step 4: Weight is NOT the same as mass — mass is 60 kg but weight is 588 N. Step 5: The unit of weight is Newton (N), not kg. Answering 60 N is a very common mistake — remember to multiply by g.