Forces and Friction

What is the difference between contact and non-contact forces?

• Contact forces occur when two objects are in direct physical contact, while non-contact forces act at a distance without direct contact.

• Contact forces are stronger than non-contact forces, while non-contact forces are weaker than contact forces.

• Contact forces occur when two objects are in direct physical contact, while non-contact forces occur when two objects are not in direct physical contact.

• Contact forces only occur in outer space, while non-contact forces only occur on Earth.

Name the four fundamental forces in nature.

• heat, light, sound, pressure

• gravity, electromagnetism, weak nuclear force, strong nuclear force

• friction, tension, compression, torsion

• attraction, repulsion, expansion, contraction

Explain the difference between balanced and unbalanced forces.

• Balanced forces have equal magnitude and opposite direction, resulting in no change in motion. Unbalanced forces have unequal magnitude or are not opposite in direction, resulting in a change in motion.

• Balanced forces have equal magnitude and same direction, resulting in a change in motion. Unbalanced forces have equal magnitude and opposite direction, resulting in no change in motion.

• Balanced forces have unequal magnitude or are not opposite in direction, resulting in no change in motion. Unbalanced forces have equal magnitude and same direction, resulting in a change in motion.

• Balanced forces have unequal magnitude or are not opposite in direction, resulting in a change in motion. Unbalanced forces have equal magnitude and opposite direction, resulting in no change in motion.

What is frictional force and how does it affect motion?

• Frictional force is the force that has no effect on the motion of an object when it is in contact with another object.

• Frictional force is the force that opposes the motion of an object when it is in contact with another object. It affects motion by slowing down the object and causing it to come to a stop.

• Frictional force is the force that increases the speed of an object when it is in contact with another object. It affects motion by making the object move faster.

• Frictional force is the force that causes an object to move in a straight line when it is in contact with another object.

List the factors that affect the magnitude of frictional force.

• Nature of surfaces, normal force, presence of lubricants or contaminants

• Shape, size, density

• Velocity, time, distance

• Temperature, color, weight

What is static friction and how is it different from kinetic friction?

• Static friction causes an object to move, while kinetic friction keeps it at rest.

• Static friction and kinetic friction are the same thing.

• Static friction only occurs on rough surfaces, while kinetic friction only occurs on smooth surfaces.

• Static friction keeps an object at rest, while kinetic friction opposes the motion of an object.

Calculate the force required to move a 50 kg object with a coefficient of friction of 0.3.

• 75 N

• 100 N

• 147 N

• 50 N

A force of 20 N is applied to a 5 kg object. What is the acceleration of the object?

• 6 m/s^2

• 2 m/s^2

• 4 m/s^2

• 10 m/s^2

Explain the concept of net force and how it affects an object's motion.

• Net force is the force exerted by an object, and it has no effect on the object's motion.

• Net force is the force of gravity acting on an object, causing it to remain at rest.

• Net force is the force applied to an object, and it causes the object to move in the opposite direction.

• Net force is the overall force acting on an object, taking into account all the individual forces. It affects an object's motion by causing it to accelerate in the direction of the net force.

What is the formula to calculate force?

• force = mass x acceleration

• force = distance / time

• force = velocity x time

• force = weight x distance