A woman wearing high-heeled shoes stands on a wooden floor. Her total weight is 480N and acts equally on each foot.

Why are marks left on the wooden floor by the woman's shoe heels but not her shoe soles?

The marks left on the wooden floor by the woman's shoe heels but not her shoe soles can be explained by the concepts of pressure and contact area.

When the woman stands on the wooden floor, the force of her weight, which is 480N, is acting on both of her feet equally. However, because of the small surface area of the heels compared to the soles of the shoes, the pressure exerted by the heels on the wooden floor is much higher.

Pressure is defined as the force applied per unit area. Since the weight of the woman is the same on both her heels and soles, the pressure exerted by her heels is much greater because the surface area in contact with the floor is smaller.

The wooden floor is relatively soft and prone to indentation. When the woman's weight is concentrated onto a smaller area, the pressure becomes high enough to create enough force to scratch or dent the wooden surface, leaving marks behind. On the other hand, the larger surface area of the shoe soles distributes the woman's weight more evenly, resulting in lower pressure per unit area. As a result, the shoe soles do not exert enough force to leave marks on the wooden floor.

To visualize this, you can try standing on a soft surface like sand or mud, first with your heels and then with the soles of your feet. You will notice that the heels sink in and leave a mark, while the soles do not.

So, the difference in the marks left by the woman's shoe heels and soles is primarily due to the difference in pressure exerted by the smaller contact area of the heels compared to the larger contact area of the soles on the wooden floor.