1. An object is moving to the right in a straight line. The net force acting on the object is also directed to the right, but the magnitude of the force is decreasing with time. How will the motion of the object change?

a. It will continue to move to the right, its speed increasing with time.
b. It will stop and then begin moving to the left.
c. It will continue to move to the right at a constant speed.
d. It will continue to move to the right, its speed decreasing with time.

2. A glass table top is able to exert a maximum normal force of 1600 N. A large object with a mass of 165 kg is gently lowered onto the center of the table top, then released there. What most likely will happen next?

a. The table top will crack but still hold the object.
b. The table top will break and the object will fall to the floor.
c. The object will bounce off the table.
d. The object will rest on the table top, which remains in tact.

3. A rock at rest has weight 138 N. What is the weight of the rock when it is accelerating upward at 12 m/s2?

a. 115 N
b. 63 N
c. 304 N
d. 138 N

4. A chair of mass 30.0 kg is at rest on a horizontal floor. The floor is not frictionless. You push on the chair with a force of 80.0 N directed at an angle of 35.0° to the floor. What is the normal force that the floor exerts on the chair?

a. 363 N
b. 340 N
c. 294 N
d. 317 N

5. Two particles are separated by a distance d. At this distance, the strong interaction between them is much greater than the electrical interaction. What are the possible values of d?

a. extremely large values, such as the distances between the planets and sun
b. extremely small values, such as the distances between particles in an atomic nucleus
c. values between 1 mm and 1 m
d. values between 1 m and 1 km

6. A soccer player kicks a ball. Why does the action force exerted by the player's foot cause a different motion than the reaction force?

a. The action force and the reaction force act on different objects.
b. The action force is greater than the reaction force.
c. The reaction force is greater than the action force.
d. The action force and the reaction force act in opposite directions.

7.
A box of weight 320 N is being pulled to the right by a pulling force F-> of magnitude 44 N. The coefficient of static friction between the box and the floor is 0.15. To make an accurate free-body diagram of the box, the letter f in the diagram above should be replaced with the label _____.

a. 4.0 N
b. 48 N
c. 44 N
d. 280 N

8. I have the answer

9. A man pulls a wagon with a handle that is at an angle of 42° with the ground. If the man pulls with 330 N of force, how much force pulls the wagon forward?

a. 110 N
b. 220 N
c. 245 N
d. 330 N

10.
In this free-body diagram, the weight (W) and normal force (n) have equal magnitudes. The magnitudes of any forward or backward forces, however, are not determined. The free-body diagram will not apply to which of these objects or persons?

a. a box sliding across a table at constant speed
b. an automobile accelerating on a flat highway
c. a box at rest on a table
d. a woman jumping off the floor

11. A force of 1 N will cause a mass of 1 kg to have an acceleration of 1 m/s2. Therefore, a force of 8 N applied to a mass of 1 kg will cause it to accelerate at what rate?

a. 8 m/s2
b. 0.13 m/s2
c. 1 m/s2
d. 9 m/s2
e. 64 m/s2

1 An object is moving to the right in a straight line The net force acting on the object is also directed to the right but the magnitude of the force is decreas class=
1 An object is moving to the right in a straight line The net force acting on the object is also directed to the right but the magnitude of the force is decreas class=

Respuesta :

1. I am definitely sure that correct option is: a. It will continue to move to the right, its speed increasing with time. If the object is experiencing a net force to the right, it always accelerates to the right => the velocity is increasing, because the greater the force, the larger the acceleration.

2. In my opinion the answer should be 
b. The table top will break and the object will fall to the floor. We should count the normal force of the object. According to the conditions, we can use N=mg; N=165*9,8 = 1617 N. 1617 > 1600. That's why I've picked this option.

3. It's tricky question, because the weight of the rock depends only on the force of gravity. Speed doesn't affect the weight of the object. So it doesn't matter what the acceleration is, its force will be 138 N. So the answer is D.

4. The friction doesn't matter. We should use Newton's laws to define 
the normal force that the floor exerts on the chair. 
So the solution is:
[tex] m*g + 80*sin(35)[/tex]; where [tex]g = 9.8;[/tex]
[tex]30*9.8 + 80*sin(35) = 342 N[/tex];
so the most approximate answer is B. 340 N.

5. I am pretty sure that correct answer is: b. extremely small values, such as the distances between particles in an atomic nucleus. According to its definition, strong interaction is a mechanism that is responsible responsible for the acts between subatomic particles of matter.

6. As far as I remember the correct option is: 
a. The action force and the reaction force act on different objects. Action and reaction forces are very important forces of a single interaction and they are not exist without each other. They're both equal in strength but opposite in direction.

7. I am not completely sure, but I think that the answer should be 48 N. We have normal force which is equal to the box's weight, so n = 320 N. Then we can count force of friction using the formula f = n*
μ where μ = 0.15. 
[tex]f = 320*0.15;[/tex]
[tex]f = 48;[/tex]
The answer is B.

8. -

9. We have 
[tex] F_{ \alpha} = 330 N[/tex] and [tex] \alpha = 42[/tex]. And this is all we need to find the real force that pulls the wagon forward.
The formula is: 
[tex] F_{f}=F_{\alpha}*cos( \alpha)[/tex];
[tex] F_{f}=330*cos(42)=244,2[/tex];

So the most approximate answer is C. 245 N.

10. According to the free-body diagram given above, the answer should be d. a woman jumping off the floor. Because in this option the object is experiencing a vertical acceleration, and this means that the normal force acting on the object will not be equal to the weight of the object.

11. According to the Newton's second law of motion [tex]F=ma => a=f/m.[/tex]
[tex]a = 8N/1kg = 8 m/s^2[/tex]
So the answer is  A. 8 m/s^2

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