Chapter 2.2, Problem 21R

To determine

To compare: the momentum of an elephant and a dolphin.

Answer to Problem 21R

The momentum of the elephant is larger than momentum of dolphin.

Explanation of Solution

Given:

Mass of an elephant is $m_1=6300\text{kg}$ .

The speed of that elephant is $v_1=0.11\text{m/s}$ .

Mass of a dolphin is $m_2=50\text{kg}$ .

The speed of the dolphin is $v_2=10.40\text{m/s}$ .

Formula used:

The equation for the momentum of the car can be expressed as

  $p=mv$....................(1)

Here, $v$ and $m$ are speed and mass.

Calculation:

For the elephant, momentum will be

  $p_1=m_1{v}_1$....................(2)

For the dolphin, the momentum will be

  $p_2=m_2{v}_2$....................(3)

Substitute $6300\text{kg}$ for $m_1$ and $0.11\text{m/s}$ for $v_1$ in equation (2)

  $\begin{array}{l}{p}_1=\left(6300\text{kg}\right)\times \left(0.11\text{m/s}\right)\\ \boxed{p_1=693\text{kg}\cdot \text{m/s}}\end{array}$

Substitute $50\text{kg}$ for $m_2$ and $10.40\text{m/s}$ for $v_2$ in equation (2)

  $\begin{array}{l}{p}_2=\left(50\text{kg}\right)\times \left(10.40\text{m/s}\right)\\ \boxed{p_2=520\text{kg}\cdot \text{m/s}}\end{array}$

Conclusion:

Hence, the momentum of the elephant is larger than momentum of dolphin.