Question

When a bullet is fired from a rifle its momentum becomes 20 kg m/s. If the velocity of the bullet is 1000 m/s, then what is its mass?

• A. 30 g
• B. 5 kg
• C. 20 g
• D. 500 g

Answer 1

Answer: (C)

20 g

Answer 2

The momentum ($p$) of an object is defined as the product of its mass ($m$) and its velocity ($v$). The formula is: $p = mv$

Given: Momentum, $p = 20$ kg m/s Velocity, $v = 1000$ m/s

To find the mass ($m$), we rearrange the formula: $m = \frac{p}{v}$

Substitute the given values: $m = \frac{20 \text{ kg m/s}}{1000 \text{ m/s}}$ $m = 0.02 \text{ kg}$

To convert the mass from kilograms to grams, we use the conversion factor 1 kg = 1000 g: $m = 0.02 \text{ kg} \times 1000 \text{ g/kg}$ $m = 20 \text{ g}$