Newton’s First & Second Laws

- With one exception, each of the following units can be used to express mass. What is the exception?
- A) newton
- B) slug
- C) gram
- D) N•s
^{2}/m - E) kilogram

- Complete the following statement: The term
*net force*most accurately describes - A) the mass of an object
- B) the inertia of an object.
- C) the quantity that causes a displacement.
- D) the quantity that keeps an object moving.
- E) the quantity that changes the velocity of an object.

Newton’s First & Second Laws

- Which one of the following terms is used to indicate the natural tendency of an object to remain at rest or in motion at a constant speed along a straight line?
- A) velocity
- B) inertia
- C) acceleration
- D) equilibrium
- E) force
- A net force is required to give an object with mass
*m*an acceleration**a**. If a net force 6 is applied to an object with mass 2*m*, what is the acceleration on this object? - A)
- B) 2
- C) 3
- D) 4
- E) 6

- When the net force that acts on an object is 96 N, the object accelerates at a rate of 48 m/s
^{2}. Determine the mass of the object. - A) 25 kg
- B) 0 kg
- C) 0 kg
- D) 5 kg
- E) 0 kg

Newton’s First & Second Laws

- A net force of 25 N is applied for 5.7 s to a 12-kg box initially at rest. What is the speed of the box at the end of the 5.7-s interval?
- A) 8 m/s
- B) 12 m/s
- C) 0 m/s
- D) 5 m/s
- E) 30 m/s

- A 975-kg car accelerates from rest to 26.7 m/s in a distance of 120 m. What is the magnitude of the average net force acting on the car?
- A) 740 N
- B) 2900 N
- C) 91 N
- D) 1300 N
- E) 7900 N

- A 2150-kg truck is traveling along a straight, level road at a constant speed of 55.0 km/h when the driver removes his foot from the accelerator. After 21.0 s, the truck’s speed is 33.0 km/h. What is the magnitude of the average net force acting on the truck during the 21.0 s interval?
- A) 2250 N
- B) 626 N
- C) 1890 N
- D) 972 N
- E) 229 N

Newton’s First & Second Laws

9 Two forces act on a 16-kg object. The first force has a magnitude of 68 N and is directed 24° north of east. The second force is 32 N, 48° north of west. What is the acceleration of the object resulting from the application of these two forces to the object?

- A) 6 m/s
^{2}, 5.5° north of east - B) 9 m/s
^{2}, 18° north of west - C) 4 m/s
^{2}, 34° north of east - D) 6 m/s
^{2}, 5.5° north of west - E) 1 m/s
^{2}, 52° north of east

- An apple crate with a weight of 175 N accelerates along a
*frictionless*surface as the crate is pulled with a force of 14.5 N as shown in the drawing.

What is the horizontal acceleration of the crate?

- A) 40 m/s
^{2} - B) 768 m/s
^{2} - C) 29 m/s
^{2} - D) 597 m/s
^{2} - E) 644 m/s
^{2}

Newton’s First & Second Laws

- Two forces act on a 6.7-kg block resting on a frictionless surface as shown. What is the magnitude of the horizontal acceleration of the block?

- A) 8 m/s
^{2} - B) 2 m/s
^{2} - C) 82 m/s
^{2} - D) 2 m/s
^{2} - E) 9 m/s
^{2}

- E) The magnitude of the acceleration will be the same in all four cases shown above.

**Newton’s Third Law**

** **

A horse pulls a cart along a flat road. Consider the following four forces that arise in this situation.

(*1*) the force of the horse pulling on the cart (*3*) the force of the horse pushing on the road

(*2*) the force of the cart pulling on the horse (*4*) the force of the road pushing on the horse

- Which two forces form an “action-reaction” pair that obeys Newton’s third law?
- A)
*1*and*4* - B)
*1*and*3* - C)
*2*and*4* - D)
*3*and*4* - E)
*2*and*3*

Newton’s First & Second Laws

- Suppose that the horse and cart have started from rest; and as time goes on, their speed increases in the same direction. Which one of the following conclusions is correct concerning the magnitudes of the forces mentioned above?
- A) Force
*1*exceeds force - B) Force
*2*is less than force - C) Force
*2*exceeds force - D) Force
*3*exceeds force - E) Forces
*1*and*2*cannot have equal magnitudes.

A book is resting on the surface of a table. Consider the following four forces that arise in this situation:

(*1*) the force of the earth pulling on the book (*3*) the force of the book pushing on the table

(*2*) the force of the table pushing on the book (*4*) the force of the book pulling on the earth

Newton’s First & Second Laws

- Which two forces form an “action-reaction” pair that obeys Newton’s third law?
- A)
*1*and*2* - B)
*1*and*3* - C)
*1*and*4* - D)
*2*and*4* - E)
*3*and*4*

- Determine the magnitude of the acceleration of the spacecraft.
- A) 6 m/s
^{2} - B) 36 m/s
^{2} - C) 5 × 10
^{–3}m/s^{2} - D) 0 × 10
^{–3}m/s^{2} - E) 06 × 10
^{–3}m/s^{2}

^{APA.}