Question

The force, F (Newtons), between two objects is inversely proportional to the square of the distance, d (metres), between them.

The force is 0.006 Newtons when the distance between the objects is 4 metres.
Work out d (rounded to 2 DP) when F=0.045 Newtons.​

Answer 1

d = 1.46 m

Explanation:

We'll begin by obtaining the relationship between the force (F) and the distance (d). This can be obtained as follow:

From the question given above,

F is inversely proportional to square of d. This can be written as:

F ∝ 1/d²

F = K/d²

Cross multiply

K = Fd²

But:

Force (F) = 0.006 N

Distance (d) = 4 m

Constant (K) =?

K = Fd²

K = 0.006 × 4²

K = 0.006 × 16

K = 0.096 Nm²

Therefore, the relationship between the force (F) and the distance (d) is:

F = K/d²

F = 0.096 / d²

Finally, we shall determine the distance when the force is 0.045 N. This can be obtained as follow:

Force (F) = 0.045 N

Constant (K) = 0.096 Nm²

Distance (d) =?

F = K/d²

0.045 = 0.096 / d²

Cross multiply

0.045 × d² = 0.096

Divide both side by 0.045

d² = 0.096 / 0.045

Take the square root of both side.

d = √(0.096 / 0.045)

d = 1.46 m.