In research in cardiology and exercise physiology, it is often important to know the mast of blood pumped by a person’s bran in one stroke. This information can be obtained by means of a ballistocardiograph . The instrument works as follows: The subject lies on a horizontal pallet floating on a film of air. Friction on the pallet is negligible. Initially, the momentum of the system is zero. When the heart beats, it expels a mass m of blood into the aorta with speed v , and the body and platform move in the opposite direction with speed V . The speed of the blood tan be determined independently (e.g., by observing an ultrasound Doppler shift). Assume that the blood’s speed is 50.0 cm/s in one typical trial. The mass of the subject plus the pallet is 54.0 kg. The pallet moves at a speed of 6.00 × 10 −5 m in 0.160 s after one heartbeat. Calculate the mass of blood that leaves the heart. Assume that the mass of blood is negligible compared with the total mass of the person. This simplified example illustrates the principle of ballistocardiography, but in practice a more sophisticated model of heart function is used.
In research in cardiology and exercise physiology, it is often important to know the mast of blood pumped by a person’s bran in one stroke. This information can be obtained by means of a ballistocardiograph . The instrument works as follows: The subject lies on a horizontal pallet floating on a film of air. Friction on the pallet is negligible. Initially, the momentum of the system is zero. When the heart beats, it expels a mass m of blood into the aorta with speed v , and the body and platform move in the opposite direction with speed V . The speed of the blood tan be determined independently (e.g., by observing an ultrasound Doppler shift). Assume that the blood’s speed is 50.0 cm/s in one typical trial. The mass of the subject plus the pallet is 54.0 kg. The pallet moves at a speed of 6.00 × 10 −5 m in 0.160 s after one heartbeat. Calculate the mass of blood that leaves the heart. Assume that the mass of blood is negligible compared with the total mass of the person. This simplified example illustrates the principle of ballistocardiography, but in practice a more sophisticated model of heart function is used.
Solution Summary: The author explains that the mass of blood that leaves the heart is 40.5g.
In research in cardiology and exercise physiology, it is often important to know the mast of blood pumped by a person’s bran in one stroke. This information can be obtained by means of a ballistocardiograph. The instrument works as follows: The subject lies on a horizontal pallet floating on a film of air. Friction on the pallet is negligible. Initially, the momentum of the system is zero. When the heart beats, it expels a mass m of blood into the aorta with speed v, and the body and platform move in the opposite direction with speed V. The speed of the blood tan be determined independently (e.g., by observing an ultrasound Doppler shift). Assume that the blood’s speed is 50.0 cm/s in one typical trial. The mass of the subject plus the pallet is 54.0 kg. The pallet moves at a speed of 6.00 × 10−5 m in 0.160 s after one heartbeat. Calculate the mass of blood that leaves the heart. Assume that the mass of blood is negligible compared with the total mass of the person. This simplified example illustrates the principle of ballistocardiography, but in practice a more sophisticated model of heart function is used.
is shown in fig (1),m2 = 2 kg, h2 = 3 m ,ml = 4 kg, , hl = 0.95 m, and µk = 0.25.
estimate (a) the velocity vl of mass ml as it hits the ground.(b) the kineticenergy of ml
m2
m1
h2
On a frictionless canvas a 5.5 kg block can slide along the x-axis and is subjected to a force of 80 N
in the +x direction while it travels 10 m. The block is initially at rest.
(c) By impulse-momentum theorem, solve the final speed after the block has moved 10 m.
on the glassy ice, a 70 kg skater sits. He propels himself forward by shooting a 3 kg ball horizontally at a pace of 8 m/s. After shooting the puck, how fast can the skater move? The coefficient of friction between the ice and the skated is f = 0.02.
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