Two objects have a force of gravity of 100 N. If the distance between both objects decreases by a factor of 7, while the masses both decrease by a factor of 8. What is the new Fg?

The gravitational force F between two masses M and m a distance r apart is

F = G M m / r ²

Decrease the distance by a factor of 7 by replacing r with r / 7, and decrease both masses by a factor of 8 by replacing M and m with M / 8 and m / 8, respectively. Then the new force F* is

F* = G (M / 8) (m / 8) / (r / 7)²

F* = (1/64 × G M m) / (1/49 × r ²)

F* = 49/64 × G M m / r ²

In other words, the new force is scaled down by a factor of 49/64 ≈ 0.7656, so the new force has magnitude approx. 76.56 N.

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.