Which of the following objects would escape from Earth's gravity? a. a tennis ball traveling at \(41,000 \mathrm{km} / \mathrm{h}\), straight up b. a bear traveling at \(41,000 \mathrm{km} / \mathrm{h}\), straight up c. a car traveling at \(41,000 \mathrm{km} / \mathrm{h}\), straight up d. an airplane traveling at \(41,000 \mathrm{km} / \mathrm{h}\), straight up

Gravitational attraction is the force that pulls objects toward one another. It's the reason why objects fall to the ground and why planets orbit the sun. This force depends on two main factors: the mass of the objects and the distance between them.

For objects on Earth, this means we're pulled towards the center of the planet. The more massive the Earth, the stronger the gravitational pull.

• Mass: The greater the mass of an object, the stronger its gravitational pull.
• Distance: The closer two objects are, the stronger the gravitational force between them.

These principles apply universally, meaning every celestial body—whether it's a moon, planet, or star—has its own gravitational field. The Earth, being quite massive, has a significant gravitational attraction, influencing everything from the path of satellites to the fall of an apple.

Minimum speed, often referred to as escape velocity, is the speed an object needs to escape the gravitational pull of a massive body without any additional propulsion. For Earth, this value is around 11.2 km/s or 40,320 km/h.

To understand escape velocity better, imagine throwing a ball into the air. If thrown too slowly, it will eventually fall back to the ground. If thrown at escape velocity, it would continue upward indefinitely, overcoming the gravitational pull of the Earth.

Here’s why it's important:

• If an object attains at least this speed, it can leave Earth's atmosphere and enter space.
• A lower speed means the object will be pulled back to the Earth's surface.
• The higher the escape velocity, the harder it is to leave the gravitational influence of the body.

All objects in the given exercise travel at 41,000 km/h, which is slightly above Earth's escape velocity. This means each of them—whether a tennis ball, bear, car, or airplane—has the minimum speed required to overcome Earth's gravity and escape into space.

Earth's gravity is the force that gives weight to objects and pulls them toward the center of the Earth. This gravitational force keeps the atmosphere intact and sustains life by holding everything close to the surface.

Several factors influence Earth's gravity:

• Mass of Earth: Earth's large mass creates a strong gravitational pull.
• Distance from the center: Gravity decreases as you move further away from the Earth's center.

Gravity affects everything from the flow of rivers to the path of satellites orbiting the planet. It's also the reason why we need a specific escape velocity to break free from this pull.

Earth's gravity not only keeps everything anchored but also influences a huge range of natural phenomena, including ocean tides and weather patterns. Without it, life as we know it wouldn't be possible. In the context of the exercise, understanding Earth's gravity helps explain why objects need a certain speed to overcome this powerful force.