# Question 27-Chemical and Physical Foundations of Biological Systems Practice Test for the MCAT

What is the acceleration of the hospital bed in the attachment?

The branch of physics that studies the motion of a body without taking into account the causes of that motion is called kinematics. According to kinematics, the position and velocity of a moving body is described by the following equations:

$X_f = X_o + V_o \cdot t + \frac{1}{2} a \cdot t^2 \ \ \ \ (1)$ $V_f=V_o+a \cdot t \ \ \ \ (2)$

Where $$X_o$$ and $$X_f$$ are the initial and final positions of the body, $$V_o$$ and $$V_f$$ are the initial and final velocities of the body, $$a$$ is the acceleration of the body, and $$t$$ is the time.

According to classical mechanics, developed by Isaac Newton, the product of the mass and the acceleration of a body can be described by the following equation (Newton’s second law):

$m \cdot a = \Sigma F$

Where $$m$$ is the mass, $$a$$ is the acceleration, and $$\Sigma F$$ is the sum of all forces acting on the body.

The following table shows the position at different times of a $$80$$-kg hospital bed with a $$40$$-kg patient on top of it that is being pushed from rest by a doctor on a rough floor that exerts a constant friction force of $$600$$ N.

Time (s) Position (m)
0 0
1 2
2 8
3 18
4 32
5 50
6 72

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