Understanding Contact and Non-Contact Forces and Gravity

The video tutorial explains the differences between contact and non-contact forces, focusing on gravity as a non-contact force. Contact forces require physical contact between objects, such as friction, air resistance, tension, and normal reaction. Non-contact forces, like gravitational, electrostatic, and magnetic forces, act even when objects are not touching. The gravitational force is a non-contact force of attraction between masses, and the weight of an object is a specific case of gravitational force between the object and Earth. The video also demonstrates how to calculate weight using the formula w = mg, with examples involving a ball and a feather.

Which of the following is a contact force?

• Magnetic force

• Electrostatic force

• Gravitational force

• Friction

What is a characteristic of non-contact forces?

• They require physical contact between objects.

• They can act over a distance without direct contact.

• They are weaker than contact forces.

• They act only when objects are touching.

Which force is responsible for pulling objects towards the Earth?

• Electrostatic force

• Gravitational force

• Magnetic force

• Tension force

How is the weight of an object calculated?

• Weight = mass x acceleration

• Weight = mass x force

• Weight = mass x gravitational field strength

• Weight = mass x velocity

If a feather has a mass of 20 grams, what is its weight on Earth?

• 0.196 Newtons

• 196 Newtons

• 1.96 Newtons

• 19.6 Newtons