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23 Nov 2019

Consider a bird that flies at an average speed of 10.7 and releases energy from its body fat reserves at an average rate of 3.70 (this rate represents the power consumption of the bird). Assume that the bird consumes of fat to fly over a distance without stopping for feeding. How far will the bird fly before feeding again?

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Irving Heathcote
Irving HeathcoteLv2
29 Mar 2019

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Related textbook solutions

Physics: Principles with Applications
7th Edition, 2013
Giancoli
ISBN: 9780321625922

Related questions

Cautious Carol (C2) eases over into the fast lane of the freeway ata speed of 70 mph. Tailgater Tommy (T2) , using his cell phone andadjusting the radio, comes blasting up behind her to within 2.5 mof her rear bumper before slowing to an identical speed. SuddenlyCarol has to panic stop due to a highway obstruction. Tommy’sreaction time, lengthened due to distractions to 0.75 s, combinedwith his tailgating habit has dire consequences. Even assuming thatboth car’s slow down at the same rate there will be a collision.Let’s assume that the magnitude of the braking acceleration is 0.7g (= 6.86 m/s2) and answer the following questions.

1. What is the initial speed of T2 and C2 in m/s?
2. If no collision occurred, what would be C2’s stopping distance(in m)?
3. Measured from the point where C2 hits the brakes, how far doesshe travel before T2 rear-ends her (in m)?
4. What is the difference in their speeds (in m/s) when theycollide?
5. What would be the minimum safe following distance (in m) for T2at these speeds?

Does the last result make sense of the recommended followingdistance of 1 car length per every 10 mph of speed?

Part A.

Blocks A, B, and C are pushed across a frictionless table by a hand that exerts a constant horizontal force. Block A has mass 2M block B has mass 3M and block C has mass M.

a) Draw separate free-body diagrams for each of the three blocks. Clearly label the forces. in the spaces below, draw vectors to represent the net force on each block.
b) Draw the vectors with correct relative magnitudes.

Part B.

Blocks A and B are at rest on a level, frictionless surface. Block B is attached to an ideal massless spring of constant k, which is initially at its equilibrium length. Block B has greater mass than block A (mB > mA).

During the interval from t1 to t2 a hand pushes block A to the left with a constant force of magnitude F0, compressing the spring a distance as shown. At time t2, both blocks again have a speed of zero.

Consider system A consisting of block A and system BS consisting of block B and the spring.

c) During the interval from t1 to t2, is the absolute value of the net work done on system BS by external forces, greater than, less than, or equal to that done on system A by external forces?

 

 

At some later time, the hand is holding the blocks at rest with the spring compressed a distance d0. At time t3 the hand releases the blocks. At time t4, the spring returns to its equilibrium length and both blocks have speed vf, as shown.

Consider the interval from t3 to t4:

d) Is the change in kinetic energy of system BS greater than, less than, or equal to that of system A?
e) Is the change in total energy of system BS positive, negative, or zero?

c) During the interval from t1 to t2, is the absolute value of the net work done on system BS by external forces, greater than, less than, or equal to that done on system A by external forces?

 

 

At some later time, the hand is holding the blocks at rest with the spring compressed a distance d0. At time t3 the hand releases the blocks. At time t4, the spring returns to its equilibrium length and both blocks have speed vf, as shown.

Consider the interval from t3 to t4:

d) Is the change in kinetic energy of system BS greater than, less than, or equal to that of system A?
e) Is the change in total energy of system BS positive, negative, or zero?

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