A good example that illustrates the law of acceleration is a car's increasing velocity. When a person pushes down the gas pedal, the car has positive acceleration. When the brakes are applied over a period of time, the vehicle accelerates in the negative direction. Another example is throwing a football. It travels in the direction of the line of action of a throw’s force at a speed that’s inversely proportional to the football’s mass and directly proportional to the force.Continue Reading
Additionally, when a person steps on a weighing scale, the number that appears on the scale is not exactly the person’s mass, which remains constant. It is his weight, and this changes under different accelerations. This is the reason why astronauts on the moon weigh differently than on earth.
When a person pulls a wagon containing a lesser weight than himself, the wagon's velocity changes, producing a positive acceleration. This acceleration is limited by the strength of the external force on the system.
An example of generating an external force to accelerate is the use of roller skates. It’s hard to get going when a person keeps the skates pointing forward with only the wheels in contact with the ground. To start moving, a sideways push on the wheels is necessary. However, wheels can’t turn sideways, so the person should push against the ground. This way, he will start to accelerate.Learn more about Motion & Mechanics
The maximum height of a projectile is calculated with the equation h = vy^2/2g, where g is the gravitational acceleration on Earth, 9.81 meters per second, h is the maximum height and vy is the vertical component of the projectile's velocity. If the angle of launch or the velocity of the projectile are not known, these quantities can be derived.Full Answer >
When the acceleration of an object is zero and the velocity is positive, the object continues to move at a steady velocity in the same direction. The object cannot be changing direction because direction change results in non-zero acceleration.Full Answer >
Deceleration is synonymous with slowing down or is related to the relative directions of velocity and acceleration. The meaning of the word in common language differs from its meaning in physics.Full Answer >
Constant acceleration is a change in velocity that doesn't vary over a given length of time. If a car increases its velocity by 20 mph over the course of a minute, then increases by another 20 mph the next minute, its average acceleration is a constant 20 mph per minute.Full Answer >