How does magnitude of force affect motion

For example, a gust of wind can speed up a sailboat. As long as the force is applied to a given object, it will to accelerate. Once the force is withdrawn, the object will continue to move at a constant velocity, according to the Law of Inertia. If an object is moving and there is an applied force in the opposite direction of the motion, the object will decelerate or slow down.

If you throw a ball up at a given velocity, it will slow down as it travels upward due to the force of gravity. Likewise, an airplane will decelerate if flying into a strong headwind. A decelerating force can cause a moving object to stop.

This can be seen when you apply the brakes on your car. A force applied at an angle to the direction of motion of an object can cause it to change direction. For years, space travel was believed to be impossible because there was nothing that rockets could push off of in space in order to provide the propulsion necessary to accelerate.

This inability of a rocket to provide propulsion in space is because It is a common misconception that rockets are unable to accelerate in space. The fact is that rockets do accelerate.

Rockets are able to accelerate due to the fact that they burn fuel and thrust the exhaust gases in a direction opposite the direction which they wish to accelerate. Many people are familiar with the fact that a rifle recoils when fired. This recoil is the result of action-reaction force pairs. A gunpowder explosion creates hot gases that expand outward allowing the rifle to push forward on the bullet. Consistent with Newton's third law of motion, the bullet pushes backwards upon the rifle.

The acceleration of the recoiling rifle is The force on the rifle equals the force on the bullet. Yet, acceleration depends on both force and mass. The bullet has a greater acceleration due to the fact that it has a smaller mass. Remember: acceleration and mass are inversely proportional. Kent Swimm, who is taking Physics for the third year in a row and not because he likes it , has rowed his boat within three feet of the dock.

Kent decides to jump onto the dock and turn around and dock his boat. Explain to Kent why this docking strategy is not a good strategy. Don't do this at home at least, not if you wish to dock the boat! As Kent jumps to reach the dock, the rowboat pushes Kent forward and thus Kent pushes the rowboat backwards.

Kent will indeed reach the dock; but Kent's rowboat will be several feet away when he turns around to dock it. That makes it very difficult for Kent to dock the boat. A clown is on the ice rink with a large medicine ball. If the clown throws the ball forward, then he is set into backwards motion with the same momentum as the ball's forward momentum. What would happen to the clown if he goes through the motion of throwing the ball without actually letting go of it?

Without actually letting go of the ball, the clown will not be displaced from his original position. There are other units of mass, including the following only the first two are accepted by the SI system :. Privacy Policy. Skip to main content. The Laws of Motion. Search for:. Force and Mass. Force Force is any influence that causes an object to change, either concerning its movement, direction, or geometrical construction.

Learning Objectives Develop the relationship between mass and acceleration in determining force. Key Takeaways Key Points Force is stated as a vector quantity, meaning it has elements of both magnitude and direction. Mass and acceleration respectively. Dynamics is the study of the force that causes objects and systems to move or deform.

External forces are any outside forces that act on a body, and internal forces are any force acting within a body. Key Terms force : A force is any influence that causes an object to undergo a certain change, either concerning its movement, direction or geometrical construction.

A common view that persists at this level is that a moving object must have a force acting on them in the direction of their motion. Some students also strongly believe that this force is being used up if the object is slowing down. Students often struggle to grasp the concept of net force, and often think it is an extra force in addition to the actual forces on an object.

The net force is the combined effect the sum of the real forces acting on the object. Net force is a valuable construct that has no separate existence of its own, unlike the real forces acting on the object, i. While the net force on an object is zero, its speed and direction of motion remain unchanged and stationary objects remain stationary.

When there is a net force on an object, it causes the object to accelerate in the direction of the net force; this is not the same as the direction of the motion unless the object is going in a straight line. Explore the relationships between ideas about force and acceleration in the Concept Development Maps — Laws of Motion. The ideas about forces and motion below contribute to student understanding of this topic. These are each covered in greater detail in the sequence of teaching ideas introduced at the lower levels:.