Indentify the direction of the netforce in each of the following situations.
A marble moves in a circular path inside a paper plate at a constant speed.
The moon orbits the earth.
An air hockey puck moves smoothly across the air hockey table after being struck.
A rocket is launched upward from the launch pad.
Thank You
There is a net force inward on the marble m v^2/R
There is a net force inward (toward earth) on the moon
m v^2/R
there is no net horizontal force on the puck. It is not accelerating.
There is a net force up on the rocket
F = change of momentum per second = mass per second of exhaust * speed of exhaust
To identify the direction of the net force in each situation, we need to consider the forces acting on the object. The net force is the vector sum of all the forces acting on an object in a particular direction.
1. A marble moving in a circular path inside a paper plate at a constant speed:
In this situation, there are two forces acting on the marble - the tension force from the string and the gravitational force. The tension force always acts radially inward toward the center of the circle, while the gravitational force acts vertically downward. The net force, which is responsible for keeping the marble moving in a circular path, is the vector sum of these two forces. The net force acts toward the center of the circle, perpendicular to the velocity of the marble.
2. The moon orbiting the Earth:
In this case, the net force acting on the moon is the gravitational force between the Earth and the moon. The gravitational force provides the centripetal force required to keep the moon in its orbit. It acts toward the center of the orbit, which is toward the Earth.
3. An air hockey puck moving smoothly across the air hockey table after being struck:
When a puck is struck on the air hockey table, there are various forces acting on it, such as the force from the striker and the frictional force between the puck and the table. The net force will depend on the magnitudes and directions of these forces. However, assuming the puck is moving with a constant speed and there is no noticeable acceleration, then the net force acting on the puck would be zero. This means that the net force is balanced, and there is no specific direction for the net force in this situation.
4. A rocket launched upward from the launch pad:
When a rocket is launched upward, there are multiple forces acting on it, including the thrust force from the engines and the gravitational force pulling it downward. Initially, the thrust force is greater than the gravitational force, causing the net force to be directed upward. This results in an upward acceleration of the rocket. However, once the rocket leaves the launch pad, the thrust force decreases, while the gravitational force remains constant. Eventually, the gravitational force becomes greater than the thrust force, causing the net force to be directed downward.