Q: A 10 kg block is pulled to the right with a force of 30 N and to the left with a force of 10 N. What is the block's acceleration?

$$a = 2 \text{ m/s}^2 to $$the right

Question 1

Which of the following best describes Newton's Second Law of Motion?

Accepted Answer

The net force on an object is equal to the product of its mass and acceleration: $$\sum F = ma$$

Question 2

A 10 kg block is pulled to the right with a force of 30 N and to the left with a force of 10 N. What is the block's acceleration?

Accepted Answer

$$a = 2 	ext{ m/s}^2 to $$the right

Question 3

Which force is always perpendicular to the surface and acts to support an object resting on it?

Accepted Answer

Normal force

Question 4

A 5 kg block is pushed to the right with 20 N and another force of 20 N to the left. What is the block's acceleration?

Accepted Answer

$$a = 0 	ext{ m/s}^2$$

Question 5

Which of the following is NOT a force acting on a suspended object?

Accepted Answer

Friction

Question 6

A 3 kg bucket is being pulled upwards by a cord. The tension in the cord is 35 N. What is the acceleration of the bucket? (Assume $$g = 10 	ext{ m/s}^2)$$

Accepted Answer

$$a = 1.7 	ext{ m/s}^2$$

Question 7

If all the forces acting on an object sum to zero, the object is in:

Accepted Answer

Equilibrium

Question 8

A 10 kg box is being lowered at a constant speed. What is the tension in the string?

Accepted Answer

$$T = 98 	ext{ N}$$

Question 9

Which of the following is the correct formula for the weight of an object?

Accepted Answer

$$W = mg$$

Question 10

A 5 kg block is suspended by two cables at equal angles. If the tension in each cable is 30 N, what is the mass of the block? (Assume $$g = 10 	ext{ m/s}^2)$$

Accepted Answer

$$m = 6 	ext{ kg}$$

Question 11

Which of the following is NOT an action-reaction pair in the scenario of a book sliding across the floor?

Accepted Answer

Weight of the book & normal force on the book

Question 12

A 1000 kg rocket is taking off from rest, accelerating vertically upward. During the first 20 seconds of its motion, the average upward force exerted by its engines is 15,000 N. What is the rocket's velocity after 20 s? (Assume $$g = 10 	ext{ m/s}^2)$$

Accepted Answer

$$v = 100 	ext{ m/s}$$

Question 13

A 2.0 kg book rests on a table. What is the normal force exerted by the table?

Accepted Answer

$$N = 19.6 	ext{ N}$$

Question 14

A 5 kg block is pushed along a frictionless surface by a force of 10 N at 37° above the horizontal. What is the block's acceleration?

Accepted Answer

$$a = 1.6 	ext{ m/s}^2$$

Question 15

Which of the following statements about gravitational acceleration is correct?

Accepted Answer

It varies depending on the location (e.g., Earth, Moon, Mars)

Question 16

Three blocks hanging from the ceiling are all connected by massless strings. Which tension supports the total weight of all three blocks?

Accepted Answer

The tension in the top-most string

Question 17

A 2D equilibrium occurs when the sum of all forces cancels out to zero in the ____ and ____ axes.

Accepted Answer

x and y

Question 18

A 5 kg block is suspended by two cables at a 30° angle with the vertical. If the tension in each cable is 50 N, what is the mass of the chandelier?

Accepted Answer

$$m = 8.7 	ext{ kg}$$

Question 19

If two blocks are connected by a string and pulled vertically upward by a force, what is the acceleration of the system if the total mass is 8 kg and the upward force is 100 N? (Assume $$g = 10 	ext{ m/s}^2)$$

Accepted Answer

$$a = 2.5 	ext{ m/s}^2$$

Intro to Forces (Dynamics): Study Notes

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