Force and acceleration

In summary, the conversation involves finding tension given velocity and acceleration in an engineering dynamics class, using the equation F=ma and a Free Body Diagram to solve for the tension in two wires suspending an engine being hoisted by a crane. The attempt at a solution includes trying F=ma and incorporating the given velocity, but the correct answer is found using \Sigma\vec{F}_y=m\vec{a}_{net}.
  • #1
erica715
1
0
This is actually for an engineering dynamics class but its basically physics. I know how to find force using F=ma. But I can't figure out how to find tension given velocity and acceleration. My book is no help :(

1. A 3.5 Mg engine is suspended from a spreader beam AB having a negligible mas and is hoisted by a crane which gives it an acceleration of 4 m/s^2 when it has a velocity of 2m/s. Determine the force in chains CA and CB during the lift. To help you visualize AB represents the distance between where the two ropes connect to the top of the engine and C is where the two ropes meet together at the crane. The angle between line AC and AB is shown as 60 degrees.


Homework Equations


F=ma


The Attempt at a Solution


First I tried the obvious F=ma. 3500kg(9.81)(4)=137340. Wrong.

Then I tried...T-cos(60)(3500)(9.81)-sin(60)(3500)(9.81)=(3500)(4)
T=26567.48. Wrong.

I feel like I need to include the velocity that's given but I have no idea where.

The answer in the back of the book says that T(of CA) and T(of CB) are both 27.9 kN.

Ugh I've been at this for a couple hours now and I only did 2 of my homework problems so far. Help please!
 
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  • #2
There are two wires which have a tension T. Draw a Free Body Diagram of the problem and list the forces.

Using [itex]\Sigma\vec{F}_y=m\vec{a}_{net}[/itex], solve for T.
 

1. What is the relationship between force and acceleration?

The relationship between force and acceleration is described by Newton's Second Law, which states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This means that the greater the force applied to an object, the greater its acceleration will be. Similarly, the larger the mass of an object, the smaller its acceleration will be for a given force.

2. How is force and acceleration measured?

Force is typically measured in units of Newtons (N) using a device called a spring scale or a force sensor. Acceleration is measured in units of meters per second squared (m/s^2) using an accelerometer or by calculating the change in velocity over time.

3. What is the difference between mass and weight?

Mass is a measure of the amount of matter in an object, while weight is a measure of the force of gravity acting on an object. Mass is typically measured in kilograms (kg) and is constant regardless of the location, while weight is measured in Newtons (N) and can vary depending on the strength of gravity at a particular location.

4. How does air resistance affect force and acceleration?

Air resistance, also known as drag, is a force that opposes the motion of an object through a fluid (such as air). This force can significantly affect an object's acceleration by reducing its net force and slowing its motion. Objects with larger surface areas or traveling at higher speeds will experience greater air resistance and therefore have a lower acceleration.

5. Can force and acceleration be negative?

Yes, force and acceleration can both be negative. A negative force indicates that the force is acting in the opposite direction of motion, while a negative acceleration indicates that an object is slowing down. This can occur when an object experiences a force in the opposite direction of its motion or when it is decelerating due to friction or air resistance.

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