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Ch 02: Motion Along a Straight Line
Young & Freedman Calc - University Physics 15th Edition
Young & Freedman Calc15th EditionUniversity PhysicsISBN: 9780135159552Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoYoung & Freedman Calc 15th EditionCh 02: Motion Along a Straight LineProblema 38b
Capitolo 2, Problema 38b

A brick is dropped (zero initial speed) from the roof of a building. The brick strikes the ground in 1.901.90 s. You may ignore air resistance, so the brick is in free fall. What is the magnitude of the brick's velocity just before it reaches the ground?

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Identify the known values: The initial velocity \( v_0 \) is 0 m/s, the time \( t \) is 1.90 s, and the acceleration due to gravity \( g \) is approximately 9.81 m/s².
Use the kinematic equation for velocity in free fall: \( v = v_0 + gt \). Since the initial velocity \( v_0 \) is zero, the equation simplifies to \( v = gt \).
Substitute the known values into the equation: \( v = 9.81 \text{ m/s}^2 \times 1.90 \text{ s} \).
Calculate the product of the acceleration due to gravity and the time to find the magnitude of the velocity just before the brick hits the ground.
The result from the calculation will give you the magnitude of the brick's velocity just before impact, which is the final answer.

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Concetti chiave

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Free Fall

Free fall refers to the motion of an object under the influence of gravitational force only, with no other forces acting on it, such as air resistance. In this scenario, the brick is in free fall, meaning it accelerates downward at a constant rate due to gravity, which is approximately 9.81 m/s² on Earth.
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Acceleration Due to Gravity

Acceleration due to gravity is the rate at which an object speeds up as it falls freely towards the Earth. It is denoted by 'g' and has a standard value of 9.81 m/s². This constant acceleration is crucial for calculating the velocity and displacement of objects in free fall, such as the brick in this problem.
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Kinematic Equations

Kinematic equations describe the motion of objects under constant acceleration. For this problem, the equation v = u + gt can be used, where v is the final velocity, u is the initial velocity (zero in this case), g is the acceleration due to gravity, and t is the time. This equation helps determine the brick's velocity just before it hits the ground.
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