Question 7 (Mandatory) (1 point) A boat travels at \( 15 \mathrm{~m} / \mathrm{s} \) on still water. On a river, the boat travels upstream against the current of \( 5.0 \mathrm{~m} / \mathrm{s} \). What is the magnitude of velocity of the boat in relation to the shore? \( 5.0 \mathrm{~m} / \mathrm{s} \) \( 10.0 \mathrm{~m} / \mathrm{s} \) \( 15.0 \mathrm{~m} / \mathrm{s} \) \( 20.0 \mathrm{~m} / \mathrm{s} \) \( 22.0 \mathrm{~m} / \mathrm{s} \)

To find the magnitude of the velocity of the boat in relation to the shore while it is traveling upstream against the current, we need to subtract the speed of the current from the speed of the boat in still water. The speed of the boat in still water is \( 15 \, \text{m/s} \) and the speed of the current is \( 5.0 \, \text{m/s} \). When the boat is going upstream, the effective speed of the boat relative to the shore is given by: \[ \text{Velocity of the boat relative to the shore} = \text{Speed of the boat} - \text{Speed of the current} \] Substituting the values: \[ \text{Velocity} = 15 \, \text{m/s} - 5.0 \, \text{m/s} = 10.0 \, \text{m/s} \] Thus, the magnitude of the velocity of the boat in relation to the shore is \( 10.0 \, \text{m/s} \). The correct answer is: \( 10.0 \, \text{m/s} \)