JEE MAIN - Physics (2008 - No. 32)
A body of mass m = 3.513 kg is moving along the x-axis with a speed of 5.00 ms−1. The magnitude of its momentum is recorded as
17.6 kg ms-1
17.565 kg ms-1
17.56 kg ms-1
17.57 kg ms-1
Explanation
Momentum, p = m $$ \times $$ v
= 3.513 $$ \times $$ 5.00 = 17.565 kg m/s
$$ \simeq $$ 17.6 kg m/s
Here number of significant digits in m is 4 and in v is 3, so, p must have minimum (which is 3) significant digit.
Note :
In this case, since we are calculating the magnitude of momentum, which is given by the absolute value of the product of mass and velocity, we should follow the rules for significant figures as if we were multiplying the two values together.
The least precise value in the calculation has three significant figures (the velocity), so we should round the answer to three significant figures as well.
Therefore, the correct answer with three significant figures is 17.6 kg m/s.
= 3.513 $$ \times $$ 5.00 = 17.565 kg m/s
$$ \simeq $$ 17.6 kg m/s
Here number of significant digits in m is 4 and in v is 3, so, p must have minimum (which is 3) significant digit.
Note :
In this case, since we are calculating the magnitude of momentum, which is given by the absolute value of the product of mass and velocity, we should follow the rules for significant figures as if we were multiplying the two values together.
The least precise value in the calculation has three significant figures (the velocity), so we should round the answer to three significant figures as well.
Therefore, the correct answer with three significant figures is 17.6 kg m/s.
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