Newton's laws problems HELP

In summary, the conversation is seeking help with various physics problems involving Newton's laws. The problems range from finding tension in ropes to determining acceleration and coefficients of friction. The person is seeking explanations and instructions to understand how to solve the problems, but is also willing to accept answers to check their own work. They acknowledge the importance of showing work, but state that it is too difficult to do so for these problems.
  • #1
psychfan29
9
0
Newton's laws problems HELP!

These are the problems that I either tried and thought I got the wrong answer :eek: or got half-way through and got completely stuck on. :bugeye: Any help would be greatly appreciated.:redface: Thanks! :wink:

1. A 43.8-kg sign is suspended by two ropes with angles of 43 and 55. Find the tension in each rope.

2. A 75-kg crate is resting on a table. The coefficient of static friction between the crate and the table top is 0.68. What is the maximum mass m of the hanging box for which the system will remain at rest?

3. An electric motor is lowering a 452-kg crate with an acceleration of 1.60m/s^2. Determine the tension in the cable.

4. A 205-kg log is pulled up a ramp by means of a rope that is parallel to the surface of the ramp. The ramp is inclined at 30 degrees with respect to the horizontal. The coefficient of kinetic friction between the log and the ramp is 0.900, and the log has an acceleration of 0.800m/s^2. Find the tension in the rope.

5. An elevator in a tall building is allowed to reach a maximum speed of 3.5m/s going down. What must the tension be in the cable to stop this elevator over a distance of 3.0m if the 3elevator has a mass of 1300kg including occupants?

6. A fisherman in a boat is using a "10-lb test" fishing line. This means that the line can exert a force of 45N without breaking (1lb=4.45N).
a) How heavy a fish can the fisherman land if he pulls the fish up vertically at a constant speed?
b) If he accelerates the fish upwards at 2.0m/s^2, what maximum weight fish can he land?

7. A block (mass m1) lying on a frictionless inclined plane is connected to a mass m2 by a massless cord passing over a pulley.
a) Determine a formula for the acceleration of the system in terms of m1, m2, theta, and g (gravity).
b) What conditions apply to masses m1 and m2 for the acceleration to be in one direction (say, m1 down the plane), or in the opposite direction?

8. Suppose the coefficient of kinetic friction between m1 and the plane (related to problem 7) is 0.15, and that m1=m2=2.7kg. As m2 moves down, determine the magnitude and direction of the acceleration of m1 and m2, given theta = 25 degrees.

9. What smallest value of the coefficient of kinetic friction will keep the system of problem 8 from accelerating?

Explanations or instructions will be helpful instead of just answers. :biggrin: I don't want to just know what the answer is. :yuck: I need to understand how to do the problem otherwise I will never pass physics. :confused: I'm here to learn.:smile: Please and thank you's! :approve:

P.S. ALTHOUGH...if you don't want to go through the trouble of explaining, the answers will at least enable me to check mine, so if that's all you're willing to do, that would help, too. THANKS!
 
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  • #2
P.S. ALTHOUGH...if you don't want to go through the trouble of explaining, the answers will at least enable me to check mine, so if that's all you're willing to do, that would help, too. THANKS!
Show us your work/answers first. You must show your work in order to get help.
 
  • #3
hage567 said:
Show us your work/answers first. You must show your work in order to get help.
It's too hard to show the work, and, as I said, some of the problems I was completely stuck on. Anyway, it's too late now. I don't need it anymore. I do understand where you're coming from, though. Thanks anyway.
 

1. What are Newton's laws of motion?

Newton's laws of motion are three fundamental principles that describe the behavior of objects in motion. The first law states that an object at rest will remain at rest and an object in motion will remain in motion at a constant velocity unless acted upon by an external force. The second law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. The third law states that for every action, there is an equal and opposite reaction.

2. How do I apply Newton's laws to solve problems?

To apply Newton's laws to solve problems, you need to first identify the forces acting on the object, including the direction and magnitude of each force. Then, you can use the equations for Newton's laws to calculate the acceleration, velocity, and position of the object. It is important to draw free body diagrams and use vector components to accurately solve these problems.

3. What is the difference between Newton's first, second, and third laws?

The first law, also known as the law of inertia, states that objects will maintain their state of motion unless acted upon by an external force. The second law describes the relationship between force, mass, and acceleration. The third law states that for every action, there is an equal and opposite reaction. Essentially, the first law explains the concept of inertia, the second law explains the relationship between force and motion, and the third law explains the concept of action and reaction.

4. What are some common real-life examples of Newton's laws?

Newton's first law can be seen in everyday situations such as a book on a table remaining at rest until someone picks it up or a car continuing to move forward even when the driver takes their foot off the gas pedal. The second law can be observed when pushing a shopping cart with a heavier load requires more force to accelerate it. The third law can be seen when a ball bounces off a wall or when a rocket launches into space.

5. How can I use Newton's laws to predict the motion of objects?

By using the equations for Newton's laws, you can calculate the acceleration, velocity, and position of an object given its mass and the forces acting upon it. This allows you to predict the future motion of an object or to analyze the past motion of an object. However, it is important to note that external factors such as friction and air resistance can also affect the motion of objects and should be taken into consideration when making predictions.

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