What is newtons 1st law

The resultant force is not zero. The submarine above has both vertical forces and horizontal forces acting on it. The horizontal forces will not affect its vertical movement and the vertical forces will not affect its horizontal movement.

The horizontal forces are equal in size and opposite in direction. They are balanced, so the horizontal resultant force is zero. This means that there is no horizontal acceleration. Momentum is defined to be the mass m of an object times its velocity V. The airplane has a mass m0 and travels at velocity V0. The mass and velocity of the airplane change during the flight to values m1 and V1.

Let us assume that the mass stays a constant value equal to m. The weight of the fuel is probably small relative to the weight of the rest of the airplane, especially if we only look at small changes in time. If we were discussing the flight of a baseball , then certainly the mass remains a constant. But if we were discussing the flight of a bottle rocket , then the mass does not remain a constant and we can only look at changes in momentum.

The change in velocity divided by the change in time is the definition of the acceleration a. The second law then reduces to the more familiar product of a mass and an acceleration:.

Remember that this relation is only good for objects that have a constant mass. This equation tells us that an object subjected to an external force will accelerate and that the amount of the acceleration is proportional to the size of the force.

Several applications are listed below. Perhaps you could think about the law of inertia and provide explanations for each application. Acquire a metal coat hanger for which you have permission to destroy. Pull the coat hanger apart. Using duct tape, attach two tennis balls to opposite ends of the coat hanger as shown in the diagram at the right.

Bend the hanger so that there is a flat part that balances on the head of a person. The ends of the hanger with the tennis balls should hang low below the balancing point. Place the hanger on your head and balance it. Then quickly spin in a circle. What do the tennis balls do? Physics Tutorial. My Cart Subscription Selection.

Student Extras. They are balanced, so the vertical resultant force is also zero. This means that there is no resultant vertical acceleration. The submarine will continue with the same motion, either remaining stationary or moving at a constant speed.

If the submarine is moving, it is impossible to tell which direction it is moving from the forces alone, only that it will continue in the same direction at the same speed. Newton's first law According to Newton's first law of motion, an object remains in the same state of motion unless a resultant force acts on it. If the resultant force on an object is zero this means: a stationary object stays stationary a moving object continues to move at the same velocity at the same speed and in the same direction Examples of objects with uniform velocity Newton's first law can be used to explain the movement of objects travelling with uniform velocity.