This photograph was taken by Apollo 8 crew member Bill Anders on December 24, 1968, showing the Earth rising above the lunar surface. Gravitational forces keep the moon orbiting the Earth.
Gravitational Force and Inclined Planes
Every object has a center of gravity. The center of gravity is the point at which the entire weight of a body may be considered to be concentrated; if supported at this point, the body would remain in equilibrium in any position. For example, if we were discussing a 12-inch ruler, the center of gravity for the ruler would be at the center of the 6-inch line. You could put your finger directly under the 6-inch line to hold the ruler and it would not fall either left or right. If you placed your finger underneath any other place on the ruler, it would fall off to one side or the other.
The triangle of the black inclined plane and the yellow triangle are similar triangles; the corresponding sides are mutually perpendicular. Therefore, the angle at the top of the yellow triangle is also 30°. For a right triangle, if we know one other angle (the 30° angle) and one side (the weight), we can calculate the other two sides. Therefore, we can calculate the parallel force pushing the box down the incline and we could also calculate the acceleration of the box.
A 500. N box is resting on a plane inclined at 30° with the horizontal.
Find the normal force and the parallel force acting on this box.
Find the acceleration of the box.
- Each object has a center of gravity, which is the point at which the weight can be considered to be concentrated when balancing the object.
- The weight of an object is a vector that is directed toward the center of the Earth.
- When an object is placed on an inclined plane, its weight vector can be resolved into the normal force, which is equal to the force of the object perpendicular to the plane, and a parallel force, which pushes the object down the inclined plane.
- A car weighing 12,000 N is parked on a 36° slope.
- Find the force tending to cause the car to roll down the hill.
- Find the acceleration of the car rolling down the hill.
Use this resource to answer the questions that follow.
- What force is broken down into components in this video?
- What two components are formed from this original force?