Final answer:
Using Hooke's Law, the force exerted by the spring with a constant k of 250 N/m extended by 3 cm is found to be 7.5 N.
Step-by-step explanation:
To determine the force exerted by a spring when it is extended, we use Hooke's Law which states that the force exerted by a spring (F) is directly proportional to the distance (x) it is stretched or compressed from its equilibrium position, mathematically expressed as F = kx. The spring constant (k) is given as 250 N/m, and the spring is extended by 3 cm (which is 0.03 m when converted to meters).
The calculation becomes:
F = kx
F = 250 N/m × 0.03 m
F = 7.5 N
So, the force exerted by the spring is 7.5 N.