Force and Motion Practice Quiz

Force is defined as a push or pull that can change an object's motion. It is a fundamental concept in physics that explains how objects interact.

Friction arises from the direct contact between two surfaces and opposes motion. Unlike forces such as gravity or magnetic force, friction requires physical contact to act.

The Newton is the standard SI unit for measuring force. It quantifies the amount of force required to accelerate a mass of one kilogram at one meter per second squared.

Force is a vector quantity because it possesses both magnitude and direction. In contrast, mass, temperature, and time are scalar quantities with only magnitude.

Gravity is the force that gives objects weight by pulling them toward the Earth. While mass is an inherent property, weight results from the gravitational pull on that mass.

According to Newton's second law (F = m × a), if the mass increases while force remains constant, the acceleration must decrease proportionally. Doubling the mass results in halving the acceleration.

Newton's Third Law states that forces always come in pairs; for every action, there is an equal and opposite reaction. This principle explains the mutual interactions between objects.

Friction is a resistive force that opposes the motion of an object across a surface. It gradually converts kinetic energy into thermal energy, causing the object to slow down over time.

Newton's First Law, also known as the law of inertia, states that objects at rest remain at rest unless acted upon by an external force. A parked car that stays stationary illustrates this principle directly.

Net force is the vector sum of all individual forces acting on an object, meaning both the magnitude and direction of each force are accounted for. This method ensures an accurate calculation of the overall force influencing the object's motion.

Friction acts to oppose the relative motion between surfaces in contact, gradually reducing the object's kinetic energy. This process ultimately brings the moving object to a stop.

Inertia is the resistance of an object to changes in its state of motion. Since inertia is directly proportional to mass, objects with greater mass have greater inertia and require more force to change their motion.

Even at a constant speed, an object moving in a circular path experiences acceleration because its direction is continuously changing. This inward acceleration, called centripetal acceleration, is always directed toward the center of the circle.

Gravity is the force that keeps planets in their elliptical orbits by pulling them toward the sun. This inward pull serves as the centripetal force necessary for maintaining orbital motion.

In collisions where objects merge, momentum is conserved provided no external forces interfere with the system. This principle is fundamental in analyzing inelastic collisions.

Using Newton's second law (F = m × a), the acceleration is calculated by dividing the net force by the mass. In this case, 50 N divided by 10 kg results in an acceleration of 5 m/s².

On a flat circular track, the friction between the tires and the road provides the centripetal force required to keep the car in circular motion. This frictional force prevents the car from sliding outward.

Weight is calculated by multiplying mass by the acceleration due to gravity (W = m × g). For a 15 kg object, 15 kg × 9.8 m/s² yields approximately 147 N.

When two perpendicular forces act on an object, the net force is found using the Pythagorean theorem. The calculation √(30² + 40²) results in 50 N.

According to Newton's second law (F = m × a), for the same acceleration, a larger mass requires a proportionally larger net force. Therefore, the heavy truck needs a greater net force compared to the small car.