Chapter 4: Further Applications of Newton's Laws: Friction, Drag, and Elasticity - Review Questions

What is the primary characteristic of friction?

a) It opposes relative motion between surfaces in contact.

b) It enhances motion between surfaces in contact.

c) It acts perpendicular to the contact surface.

d) It is independent of the nature of surfaces in contact.

a) It opposes relative motion between surfaces in contact.

Which type of friction acts when two surfaces are in contact but not moving relative to each other?

a) Kinetic friction

b) Static friction

c) Rolling friction

d) Fluid friction

b) Static friction

What is the formula for the maximum static friction?

a) fs(max) = μsN

b) fs(max) = μkN

c) fs(max) = μs/mg

d) fs(max) = μk/mg

a) fs(max) = μsN

How does the coefficient of kinetic friction compare to the coefficient of static friction?

a) It is usually greater.

b) It is usually less.

c) They are always equal.

d) It is unrelated to static friction.

b) It is usually less.

What happens to the frictional force when the normal force increases?

a) It decreases.

b) It remains constant.

c) It increases.

d) It becomes zero.

c) It increases.

The force that opposes relative motion between surfaces in contact is called ___.

friction

What role does the normal force play in friction?

The normal force is the force perpendicular to the contact surface, and it affects the magnitude of frictional force. Frictional force is proportional to the normal force.

What is the relationship between drag force and velocity for large objects moving at high speeds?

a) Drag force is proportional to velocity

b) Drag force is proportional to the square of velocity

c) Drag force is inversely proportional to velocity

d) Drag force is independent of velocity

b) Drag force is proportional to the square of velocity

What is the drag coefficient?

a) A measure of the density of the fluid

b) A dimensionless quantity that represents the drag per unit area

c) A measure of the viscosity of the fluid

d) A constant that represents the gravitational force

b) A dimensionless quantity that represents the drag per unit area

Which of the following statements is true about terminal velocity?

a) Terminal velocity is reached when the drag force equals the gravitational force.

b) Terminal velocity is the maximum speed an object can achieve in a vacuum.

c) Terminal velocity occurs when the drag force is zero.

d) Terminal velocity is independent of the object's mass.

a) Terminal velocity is reached when the drag force equals the gravitational force.

According to Stokes' Law, what is the drag force proportional to for small particles moving at low speeds?

a) The square of the velocity

b) The velocity

c) The cube of the velocity

d) The inverse of the velocity

b) The velocity

The drag force is mathematically expressed as FD = 0.5CρAv², where C is the ___, ρ is the ___ of the fluid, and A is the ___ of the object facing the fluid.

drag coefficient; density; area

Terminal velocity is achieved when the net force on the object is ___.

zero

Describe the factors that influence the terminal velocity of a skydiver.

The terminal velocity of a skydiver is influenced by the skydiver's mass, the drag coefficient, the density of the air, and the frontal area of the skydiver. A larger mass or smaller frontal area results in a higher terminal velocity, while a higher drag coefficient or greater air density results in a lower terminal velocity.

What does Hooke's Law state about the relationship between force and deformation?

a) Force is inversely proportional to deformation

b) Force is directly proportional to deformation

c) Force is independent of deformation

d) Force is equal to deformation

b) Force is directly proportional to deformation

Which of the following materials has the highest Young's modulus?

a) Aluminum

b) Steel

c) Nylon

d) Glass

b) Steel

What type of deformation occurs when a force is applied parallel to the surface of an object?

a) Tension

b) Compression

c) Shear

d) Bulk

c) Shear

Which modulus is used to describe the deformation of a material under uniform pressure?

a) Young's Modulus

b) Shear Modulus

c) Bulk Modulus

d) Elastic Modulus

c) Bulk Modulus

What is the unit of stress in the context of elasticity?

a) Pascal

b) Newton

c) Joule

d) Watt

a) Pascal

According to Hooke's Law, the force applied to an object is proportional to the ___ it causes.

deformation

Explain the concept of tensile strength in materials.

Tensile strength is the maximum stress that a material can withstand while being stretched or pulled before breaking.

What is the significance of the elastic modulus in material science?

The elastic modulus quantifies a material's resistance to deformation under stress, indicating its stiffness.