Final answer:
Using the formula for momentum P = m × v, where momentum (P) is given as 490 kg·m/s and velocity (v) is 7 m/s, the total mass (m) of the bicycle and the boy is 70 kg. The correct answer is option A.
Step-by-step explanation:
The question asks for the total mass of the bicycle and the boy when the total momentum is given.
Momentum is calculated by multiplying the mass of the object (m) by its velocity (v), expressed by the formula P = m × v. The total momentum provided in the question is 490 kg·m/s, and the bicyclist travels at a constant speed of 7 m/s.
We can calculate the mass using the equation:
m = P / v
m = 490 kg·m/s / 7 m/s
m = 70 kg
So, the total mass of the bicycle and the boy is 70 kg, which corresponds to option A.