knowverseWhen you toss an object into the air, its flight combines forward motion with a constant downward pull. Understanding how these independent components interact explains every trajectory.
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Once thrown, no horizontal force acts on the object, so it moves forward solely because of its inertia.
After the initial toss, no horizontal force acts on it (ignoring air resistance). It moves forward only because of its inertia.
From the Knowverse course text.
Physics experiments show that the horizontal motion does not care what the vertical motion is doing.
The most important discovery in physics regarding this is that these two components are independent of each other.
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The steady forward push and increasing downward pull combine to form a symmetric, U-shaped curve known as a parabola.
If we ignore air resistance, the path of any object thrown into the air is a parabola.
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For most projectiles, a launch angle of 45 degrees provides the maximum horizontal distance.
For most projectiles, a launch angle of 45 degrees provides the maximum horizontal distance.
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Gravity pulls both objects downward equally, regardless of how fast one is moving forward.
They hit at the exact same time. Gravity pulls them both downward equally, regardless of how fast one is moving forward.
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In real life, air resistance acts as drag, which slows the horizontal movement so the object travels less distance.
In real life, air resistance (drag) acts as a horizontal force that slows the projectile down.
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For a tiny moment at the peak, the object stops moving up before it begins to fall down.
Zero. For a tiny moment, the object stops moving up before it begins to fall down.
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As long as air resistance is ignored, all objects accelerate downward at the same rate regardless of mass.
No. As long as we ignore air resistance, all objects accelerate downward at the same rate ($9.8 m/s^2$) regardless of their mass.
From the Knowverse course text.
Gravity acts toward the center of the Earth, providing the inward pull required for circular orbital motion.
Gravity acts as a centripetal force that keeps the satellite in a circular path instead of flying off in a straight line.
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Astronauts and their spacecraft fall toward Earth at the exact same rate, creating continuous free-fall.
Astronauts feel weightless because they are in a state of continuous free-fall.
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See the answer and explanation for each question below.
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Projectiles on Earth handle two things at once by moving forward and falling down simultaneously. Because no horizontal force acts on the object after the initial toss, its forward speed remains completely constant.
Meanwhile, gravity exerts a constant downward force that governs the vertical side of the motion. These two components are entirely independent of each other and do not interfere with each other's progress.
If we could turn off gravity, the object would fly straight ahead forever due to its inertia. Instead, the combination of constant forward speed and downward acceleration creates a predictable path toward the ground.
On Earth, projectiles are complicated because they are doing two things at once: moving forward and falling down.
From the Knowverse course text.
The combination of steady forward motion and accelerating downward pull creates a symmetric U-shaped curve known as a parabola. This smooth arch appears every time you throw a stone or kick a ball.
Choosing the right launch angle determines how far the object travels through the air. For most projectiles, aiming at a forty-five degree angle provides the maximum possible horizontal distance.
Lightweight objects with a large surface area face heavy air resistance that pushes back against them. This drag slows the object down and causes the trajectory to drop more steeply than a mathematical parabola predicts.
If we ignore air resistance, the path of any object thrown into the air is a parabola.
From the Knowverse course text.
If you throw a stone fast enough, the curvature of the Earth itself starts to matter. Because the surface drops away at the same rate the projectile falls, the object stays at the same height.
An Earth satellite is simply a projectile that is falling around the planet rather than into it. To maintain this speed, the object must travel high enough above the atmosphere to avoid air resistance.
Gravity acts as a centripetal force that pulls toward the center of the Earth while the satellite moves sideways. Because this force is perpendicular to the motion, it changes the direction without doing work on the speed.
An Earth satellite is simply a projectile that is falling around the Earth rather than into it.
From the Knowverse course text.
Sources: Curved Motion and Gravity. Each question or step includes an excerpt from the course.
