Consider an individual whose height and weight are 1.7m and 75 kg, respectively.

Question

Consider an individual whose height and weight are 1.7m and 75 kg, respectively. When
riding in a vehicle, the individual faces forward and is restrained by a lap belt. What is the initial
angular acceleration of the upper body due to a sudden deceleration of 10*gravity ? Express
your answer in degrees per second.
Given: (note: HAT is used to mean “Head, arms and trunk”)
Mass of HAT: mHAT=50.8 kg
Height from the hips to the head: htorso= 0.578m
The center of mass of the HAT is above the hips: hcm=0.626 *htorso
The mass moment of inertia of the HAT, about its own center of mass is:
Icm_HAT=0.287 kg*m2
The mass moment of inertia of the HAT, about the hips, is:
IHip_HAT=0.287 kg*m2+ mHAT*(htorso)2

Explanation / Answer

torque about the lap belt ie hip
=F*d

where F is inertial force acting in centre of mass and di distance of centre of mass from hip

=75*10*g*.626*.578

=2713.71

=I*

2713.71=(.287+50.8*.578*.578)*

=157.2

angular acc=157.2

hope this will help u..

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