Final answer:
The gravitational force on a 25 kg object at the Earth's surface is approximately 245.25 N calculated using Newton's law of gravitation, but it is often approximated to 245 N using Earth's average acceleration due to gravity (9.80 m/s²).
Step-by-step explanation:
To calculate the force of gravity on a 25 kg object at the Earth's surface, we use Newton's universal law of gravitation. The gravitational force (F) is given by the equation F = Gm1m2/r2, where G is the gravitational constant (6.674×10-11 Nm2/kg2), m1 is the mass of the object, m2 is the mass of the Earth, and r is the radius of the Earth. Substituting the given values, we get F = (6.674×10-11)(25 kg)(5.97×1024 kg)/(6.378×106 m)2.
Calculating the above expression, we find that the gravitational force is approximately 245.25 N, which also represents the weight of the object. However, for most practical purposes, the acceleration due to gravity (g) is approximated to be 9.80 m/s2 on Earth's surface. Therefore, you can also calculate the weight directly by using the formula w = mg, which gives you (25 kg)(9.80 m/s2) = 245 N.