What are the general steps to solve for velocity when a resistive force is present?
Apply Newton's Second Law (Fnet=ma) to obtain a differential equation for velocity.
Use separation of variables to solve the differential equation by integrating with appropriate limits.
Use initial conditions to find the constants of integration.
Solve for the velocity as a function of time.
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What are the general steps to solve for velocity when a resistive force is present?
Apply Newton's Second Law (Fnet=ma) to obtain a differential equation for velocity.
Use separation of variables to solve the differential equation by integrating with appropriate limits.
Use initial conditions to find the constants of integration.
Solve for the velocity as a function of time.
How do you determine terminal velocity mathematically?
Set the derivative of velocity with respect to time equal to zero: fracdvdt=0.
Solve the resulting equation for velocity. This value is the terminal velocity.
What is the process to analyze motion with resistive forces using differential equations?
Identify all forces acting on the object, including resistive forces.
Apply Newton's Second Law to set up the differential equation.
Solve the differential equation using separation of variables and initial conditions.
Analyze the resulting velocity, position, and acceleration functions, paying attention to asymptotes and the time constant.
What are the steps to determine the time constant?
Identify the mass m of the object.
Identify the constant k in the resistive force equation (Fr=−kv).
Calculate the time constant using the formula: τ=km.
What are the steps to solve free fall problems with air resistance?
Draw a free-body diagram showing gravitational force and air resistance.
Apply Newton's second law: mg−kv=ma.
Determine the terminal velocity by setting a=0, so vt=mg/k.
If required, solve the differential equation for v(t).
What is a resistive force?
A force that opposes the motion of an object, slowing it down. It is velocity-dependent and acts in the opposite direction of motion.
Define terminal velocity.
The maximum speed an object reaches when the constant force (like gravity) and the resistive force (like air resistance) balance each other, resulting in zero net acceleration.
What is the time constant (τ)?
The time constant, τ=km, indicates how quickly an object reaches terminal velocity. A larger mass or smaller k (weaker resistive force) means a longer time to reach terminal speed.
Define k in the context of resistive force.
k is a positive constant that depends on the shape and size of the object and the properties of the medium (like air density). It appears in the resistive force equation: Fr=−kv
What is the relationship between net force and acceleration at terminal velocity?
At terminal velocity, the net force is zero, which means the acceleration is also zero. The object stops speeding up.
What is the effect of increased speed on resistive force?
The resistive force increases.
What is the effect of air resistance equaling the force of gravity?
The object stops accelerating and reaches terminal velocity.
What is the effect of a larger mass on terminal velocity?
The terminal velocity increases.
What happens when dtdv=0?
The object reaches terminal velocity and stops speeding up.
What is the effect of a larger surface area on air resistance?