Q: A car of mass $$m$$ rounds a frictionless banked curve of radius $$r at $$speed $$v. $$What is the correct expression for the banking angle $$\theta so $$that no friction is required?

$$\tan \theta = \dfrac{v^2$}{g r}$$

Q: A block of mass $$m is $$sliding down a ramp inclined at angle $$\theta$$ with coefficient of kinetic friction $$\mu_k. $$What is the acceleration of the block?

$$a = g \sin \theta - \mu_k g \cos \theta$$

Question 1

A box of mass $$m$$ rests on a horizontal surface. A horizontal force $$F is $$applied, but the box does not move. Which statement best describes the frictional force acting on the box?

Accepted Answer

The frictional force equals the applied force $$F$$, and $$f_s \u003c \mu_s n.$$

Question 2

A person stands on a scale in an elevator accelerating upward with acceleration $$a_y. $$What does the scale read?

Accepted Answer

The scale reads $$n = m(g + a_y).$$

Question 3

A car of mass $$m$$ rounds a frictionless banked curve of radius $$r at $$speed $$v. $$What is the correct expression for the banking angle $$	heta so $$that no friction is required?

Accepted Answer

$$	an 	heta = \dfrac{v^2$}{g r}$$

Question 4

Which of the following is NOT a fundamental force of nature?

Accepted Answer

Frictional force

Question 5

A ball of mass $$m is $$whirled in a horizontal circle of radius $$r at $$constant speed $$v. $$What is the magnitude of the net force acting on the ball?

Accepted Answer

$$F = \dfrac{m v^2$}{r}$$

Question 6

A box of mass $$m is $$sliding at constant speed on a horizontal surface. What is the relationship between the applied force $$F$$ and the kinetic friction force?

Accepted Answer

$$F = \mu_k n$$

Question 7

A skydiver of mass $$m$$ falls through the air and eventually reaches terminal speed. Which statement is true at terminal speed?

Accepted Answer

The net force on the skydiver is zero.

Question 8

A block of mass $$m is $$pulled by a rope at an angle $$	heta$$ above the horizontal on a rough surface. Which equation correctly expresses the normal force $$n$$ acting on the block?

Accepted Answer

$$n = m g - T \sin 	heta$$

Question 9

Which of the following statements about free-body diagrams is correct?

Accepted Answer

Only forces acting ON the object should be included.

Question 10

A box is at rest on a horizontal surface. The maximum static friction force is $$f_{s,	ext{max}} = \mu_s n. If a $$horizontal force $$F is $$applied and $$F \u003e f_{s,	ext{max}}$$, what happens?

Accepted Answer

The box accelerates and kinetic friction acts: $$f_k = \mu_k n.$$

Question 11

A spacecraft in orbit experiences 'apparent weightlessness.' What is the best explanation for this phenomenon?

Accepted Answer

The spacecraft and its occupants are in free fall, accelerating at $$g.$$

Question 12

A block of mass $$m is $$sliding down a ramp inclined at angle $$	heta$$ with coefficient of kinetic friction $$\mu_k. $$What is the acceleration of the block?

Accepted Answer

$$a = g \sin 	heta - \mu_k g \cos 	heta$$

Question 13

Which scenario best illustrates Newton's first law?

Accepted Answer

A car moving at constant velocity on a straight, frictionless road.

Question 14

A falling object experiences air resistance proportional to its speed. As it falls, what happens to its acceleration?

Accepted Answer

Acceleration decreases as speed increases.

Question 15

Which of the following is a correct statement about static and kinetic friction?

Accepted Answer

Static friction can vary up to its maximum value.

Question 16

A ball is moving in a circle attached to a string. If the string breaks, what path does the ball follow?

Accepted Answer

It moves in a straight line tangent to the circle.

Question 17

Which of the following is a common error when drawing free-body diagrams for circular motion?

Accepted Answer

Including a 'centrifugal force' acting outward.

Question 18

A caterpillar moves forward by pushing against the ground. Which force enables its movement?

Accepted Answer

Frictional force

Question 19

A windshield wiper squeaks on dry glass but not on wet glass. What physical phenomenon explains this?

Accepted Answer

Stick-slip due to static friction exceeding kinetic friction.

Question 20

Which of the following is true about the net force on an object in equilibrium?

Accepted Answer

$$\sum F_x = 0$$ and $$\sum F_y = 0$$

Chapter 05

Guida di studio - Domande di pratica

Study guide - Flashcard