Question

A 35.0-kg dolphin decelerates from 12.0 to 7.50 m/s in 2.30 s to join another dolphin in play. What average force was exerted to slow the first dolphin if it was moving horizontally? (The gravitational force is balanced by the buoyant force of the water.)

Answer 1

Answer:

68.5N

Explanation:

When the dolphin decelerates from 12m/s to 7.5 m/s within 2.3s. Then its acceleration is:

$a = \frac{\Delta v}{\Delta t} = \frac{7.5 - 12}{2.3} = -1.96 m/s^2$

The dolphin has a mass of 35kg, according to the Newton's 2nd law, the force exerted on it must be:

$F = ma = 35*1.96 = 68.5 N$