(a) Calculate the force needed to bring a 950-kg car to rest...

Name: Problem 12, Chapter 7: College Physics for AP® Courses
Uploaded: 2023-10-03T18:40:41-08:00
Duration: 4 min 12 s
Channel: Nishant Kumar
Description: (a) Calculate the force needed to bring a 950-kg car to rest from a speed of 90.0 km/h in a distance of 120 m (a fairly typical distance for a non-panic stop). (b) Suppose instead the car hits a concrete abutment at full speed and is brought to a stop in 2.00 m. Calculate the force exerted on the car and compare it with the force found in part (a).

(a) Calculate the force needed to bring a 950-kg car to rest from a speed of 90.0 km/h in a distance of 120 m (a fairly typical distance for a non-panic stop). (b) Suppose instead the car hits a concrete abutment at full speed and is brought to a stop in 2.00 m. Calculate the force exerted on the car and compare it with the force found in part (a).

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Key Concepts

Unit Conversion

Unit conversion is a key step in solving physics problems where standard units are required. A common example is converting speed from kilometers per hour to meters per second, ensuring consistency and correctness in calculations involving acceleration and force.

Work-Energy Principle

The work-energy principle relates the work done by forces acting on an object to the change in its kinetic energy. For stopping problems, it implies that the work done by the stopping force over the distance equals the reduction in kinetic energy. This principle provides an alternative method for finding the force required to stop an object.

Kinematics

This concept involves the equations of motion that relate speed, acceleration, displacement, and time under uniform acceleration. In problems like these, using the relation between initial velocity, final velocity, acceleration, and distance (such as v² = u² + 2as) is crucial to determine the deceleration required to bring an object to rest over a specified distance.

Newton's Second Law

Newton's Second Law states that the net force acting on an object is equal to the mass of the object multiplied by its acceleration (F = ma). This principle is foundational in analyzing the dynamics of objects and is used to calculate the stopping force once the deceleration is determined.

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