Quick Questions: Mass M on Horizontal Surface

  • Thread starter Amel
  • Start date
In summary, the conversation discusses the conditions for a mass M to start moving on a horizontal surface with coefficients of static and kinetic friction of 0.30 and 0.20, respectively. It is stated that the tension force T must exceed the maximum static friction force in order for M to accelerate. Additionally, if M remains at rest, the tension force must equal the maximum static friction force. Finally, it is noted that the net force on M, if it does not move, is equal to the tension force.
  • #1
Amel
43
0

Homework Statement



A mass M is initially at rest on a horizontal surface, mus=0.30 and muk=0.20 . A horizontal string then pulls M with a tension T. Forces below are magnitudes

A) N equals Mg
B) If M does not accelerate, then T less than or equal mu_s N
C) M will accelerate if T exceed mu_s N
D) M will accelerate if T exceeds mu_k N
E) T equals mu_s N if M remains at rest
F) The NET force on M (if M does not move) is T


The Attempt at a Solution



Ok so I am not sure which I am getting wrong here. I am supposed to choose which ones of them are right but I can't get it. If someone can tell me where I am messing up.

Im putting
A
B
D
E
for correct.
 
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  • #2
How hard do you have to pull to start M moving (and thus accelerating)? Remember that it starts from rest.

If you pull and it doesn't move, what can you say about the friction force? How does that friction force compare to the maximum static friction force?

(Two of your answers are wrong.)
 
  • #3


As a scientist, it is important to carefully analyze and interpret the given information. Let's break down each statement and determine if they are correct or not.

A) N equals Mg: This statement is correct. N represents the normal force, which is equal to the weight of the mass M (Mg) in this situation.

B) If M does not accelerate, then T less than or equal mu_s N: This statement is also correct. According to Newton's first law, if an object is at rest or moving at a constant velocity, the net force acting on it must be zero. In this case, the only forces acting on M are the tension force (T) and the frictional force (mu_s N). Therefore, in order for M to not accelerate, the tension force must be less than or equal to the maximum static frictional force (mu_s N).

C) M will accelerate if T exceed mu_s N: This statement is incorrect. If the tension force exceeds the maximum static frictional force, the object will overcome the frictional force and start accelerating.

D) M will accelerate if T exceeds mu_k N: This statement is correct. If the tension force exceeds the maximum kinetic frictional force (mu_k N), the object will accelerate.

E) T equals mu_s N if M remains at rest: This statement is incorrect. If the object is at rest, the tension force must be less than or equal to the maximum static frictional force (mu_s N), as stated in statement B.

F) The NET force on M (if M does not move) is T: This statement is incorrect. The net force on M (if it is not moving) is actually zero, as stated in statement B. The tension force (T) is only one of the forces acting on M, but it is not the only force.

Therefore, the correct statements are A, B, D, and E. It is important to carefully consider all the forces acting on an object and their respective magnitudes in order to accurately determine if the object will accelerate or remain at rest.
 

1. What is the formula for calculating mass?

The formula for calculating mass is mass = density x volume. Mass is typically measured in kilograms (kg), and density is measured in kilograms per cubic meter (kg/m^3).

2. How do you determine the mass of an object on a horizontal surface?

To determine the mass of an object on a horizontal surface, you will need to use a balance or scale. Place the object on the balance and record the reading. This will give you the mass of the object in kilograms.

3. Can the mass of an object change on a horizontal surface?

No, the mass of an object does not change on a horizontal surface. Mass is an intrinsic property of an object and is not affected by its position or location.

4. How does the mass of an object on a horizontal surface affect its motion?

The mass of an object on a horizontal surface does not directly affect its motion. However, it does affect the object's inertia, which is the resistance to changes in motion. Objects with larger masses have greater inertia and require more force to change their motion.

5. What is the difference between mass and weight?

Mass and weight are often used interchangeably, but they are actually two different measurements. Mass is a measure of an object's resistance to acceleration, while weight is a measure of the force of gravity acting on an object. Mass is constant, while weight can vary depending on the strength of the gravitational pull in a specific location.

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