MP trial assignment
8/29/2014
Trial Assignment: Kinematics in 1D & Vectors
Trial Assignment: Kinematics in 1D & Vectors
Due: 2:00am on Friday, August 29, 2014
To understand how points are awarded, read the Grading Policy for this assignment.
Ballistocardiograph Conceptual Question
In a ballistocardiograph, a patient lies on an extremely low friction horizontal table. At each heartbeat, a volume of blood is accelerated by the heart toward the head along the ascending aorta. In response, the patient's body recoils in the opposite direction. This motion is detected by sensitive accelerometers attached to the table. (The table is then brought to rest and returned to equilibrium before the next heartbeat.)
A graph of acceleration of the table versus time, termed a ballistocardiogram, is generated. Based on these measurements, the acceleration of the blood ejected by the heart can be determined. Patients with low blood accelerations generally have weakened heart muscles.
A sketch of a single cycle of a ballistocardiogram is given in the figure. . The units of the graph are arbitrary and linear for both time, , and acceleration, .
Part A
At what time (in the arbitrary time units of the graph) is the speed of the table (and hence the speed of the blood in the opposite direction) a maximum?
Hint 1. How to read the graph
The graph is acceleration versus time. Remember that velocity is the signed area under the acceleration curve. As long as the acceleration is positive, the speed is increasing. Once the acceleration becomes negative, the speed will begin to decrease back to zero.
ANSWER:
3
Correct
Problem 2.6
Geology. Earthquakes produce several types of shock waves. The most well-known are the P-waves (P for primary http://session.masteringphysics.com/myct/assignmentPrintView?assignmentID=2993993 1/26
8/29/2014
Trial Assignment: Kinematics in 1D & Vectors
or pressure) and the S-waves (S for secondary or shear). In the earth's crust, the P-waves travel at around 6.5 km/s while the
Trial Assignment: Kinematics in 1D & Vectors
Trial Assignment: Kinematics in 1D & Vectors
Due: 2:00am on Friday, August 29, 2014
To understand how points are awarded, read the Grading Policy for this assignment.
Ballistocardiograph Conceptual Question
In a ballistocardiograph, a patient lies on an extremely low friction horizontal table. At each heartbeat, a volume of blood is accelerated by the heart toward the head along the ascending aorta. In response, the patient's body recoils in the opposite direction. This motion is detected by sensitive accelerometers attached to the table. (The table is then brought to rest and returned to equilibrium before the next heartbeat.)
A graph of acceleration of the table versus time, termed a ballistocardiogram, is generated. Based on these measurements, the acceleration of the blood ejected by the heart can be determined. Patients with low blood accelerations generally have weakened heart muscles.
A sketch of a single cycle of a ballistocardiogram is given in the figure. . The units of the graph are arbitrary and linear for both time, , and acceleration, .
Part A
At what time (in the arbitrary time units of the graph) is the speed of the table (and hence the speed of the blood in the opposite direction) a maximum?
Hint 1. How to read the graph
The graph is acceleration versus time. Remember that velocity is the signed area under the acceleration curve. As long as the acceleration is positive, the speed is increasing. Once the acceleration becomes negative, the speed will begin to decrease back to zero.
ANSWER:
3
Correct
Problem 2.6
Geology. Earthquakes produce several types of shock waves. The most well-known are the P-waves (P for primary http://session.masteringphysics.com/myct/assignmentPrintView?assignmentID=2993993 1/26
8/29/2014
Trial Assignment: Kinematics in 1D & Vectors
or pressure) and the S-waves (S for secondary or shear). In the earth's crust, the P-waves travel at around 6.5 km/s while the