2.1. One way to measure gravitational acceleration is to simply drop an object and measure its time of flight, i.e. the time it is in air before landing. Suppose you drop an object from height h = 2 m. To minimize the effect of drag (air resistance), suppose the object is aerodynamic in shape, and has a small cross-sectional area but a large mass. Under these conditions, drag will be negligible. You will measure the time of flight using a stopwatch. 2.1.1. Suppose you measure the time of flight to be 0.639 s. Use the kinematic equations to calculate g: What is the percent difference between this value and the expected value of 9.8 m/s²? 2.1.2. Suppose you repeat the measurement to verify your results. When you repeat the measurement, you find the time of flight to be 0.739 s. Use the kinematic equations to calculate g: What is the percent difference between this value and the expected value of 9.8 m/s? The human reaction time is approximately 0.2 seconds.10 This is the minimum time required to respond to a stimulus, such as an object hitting the ground. Notice that a difference of only 0.1 seconds between the flight times – less than the human reaction time – makes a large difference in your result. This is clearly - - not a good method for measuring gravitational acceleration. 2.2. A better way to measure gravitational acceleration is to use a video camera. A video camera takes a fixed number of photographs per second. Knowing this number, you can calculate the time of flight much more accurately than a stopwatch. 2.2.1. Traditional movie cameras record video at a rate of 24 frames per second (fps). This means that 24 photographs are recorded each second. Recently, some directors choose to use cameras with higher frame rates for a "heightened sense of reality."11 Suppose you plan to use a camera with a frame rate of 40 fps. How long (in seconds) does each photograph take? In other words, what is the time interval (in seconds) between two consecutive frames?

2.1. One way to measure gravitational acceleration is to simply drop an object and measure its time of flight, i.e. the time it is in air before landing. Suppose you drop an object from height h = 2 m. To minimize the effect of drag (air resistance), suppose the object is aerodynamic in shape, and has a small cross-sectional area but a large mass. Under these conditions, drag will be negligible. You will measure the time of flight using a stopwatch. 2.1.1. Suppose you measure the time of flight to be 0.639 s. Use the kinematic equations to calculate g: What is the percent difference between this value and the expected value of 9.8 m/s²? 2.1.2. Suppose you repeat the measurement to verify your results. When you repeat the measurement, you find the time of flight to be 0.739 s. Use the kinematic equations to calculate g: What is the percent difference between this value and the expected value of 9.8 m/s? The human reaction time is approximately 0.2 seconds.10 This is the minimum time required to respond to a stimulus, such as an object hitting the ground. Notice that a difference of only 0.1 seconds between the flight times – less than the human reaction time – makes a large difference in your result. This is clearly - - not a good method for measuring gravitational acceleration. 2.2. A better way to measure gravitational acceleration is to use a video camera. A video camera takes a fixed number of photographs per second. Knowing this number, you can calculate the time of flight much more accurately than a stopwatch. 2.2.1. Traditional movie cameras record video at a rate of 24 frames per second (fps). This means that 24 photographs are recorded each second. Recently, some directors choose to use cameras with higher frame rates for a "heightened sense of reality."11 Suppose you plan to use a camera with a frame rate of 40 fps. How long (in seconds) does each photograph take? In other words, what is the time interval (in seconds) between two consecutive frames?

College Physics

1st Edition

ISBN:9781938168000

Author:Paul Peter Urone, Roger Hinrichs

Publisher:Paul Peter Urone, Roger Hinrichs

Chapter3: Two-dimensional Kinematics

Section: Chapter Questions

Problem 1CQ: Which of the following is a vector: a person's height, the altitude on Mt. Everest, the age of the...

See similar textbooks