A space probe is built with a mass of 1700 pound-mass [lb m ] before launch on Earth. The probe is powered by four ion thrusters, each capable of generating 225 millinewtons [mN] of thrust. Using Newton’s second law, the acceleration (a) of the craft is equal to the force ( F ) divided by the mass ( m ): a = F m The velocity (v) of an object increases as an object accelerates. If the object starts at rest, the final velocity is given by the acceleration multiplied by the length of time the acceleration is applied to the object (t): v = a t = F t m Using this equation, how many weeks will the thrusters have to operate for the probe, initially at rest, to reach a velocity of 420 miles per minute [mi/min]? You may assume the initial velocity of the probe is zero miles per minute [0 mi/min].
A space probe is built with a mass of 1700 pound-mass [lb m ] before launch on Earth. The probe is powered by four ion thrusters, each capable of generating 225 millinewtons [mN] of thrust. Using Newton’s second law, the acceleration (a) of the craft is equal to the force ( F ) divided by the mass ( m ): a = F m The velocity (v) of an object increases as an object accelerates. If the object starts at rest, the final velocity is given by the acceleration multiplied by the length of time the acceleration is applied to the object (t): v = a t = F t m Using this equation, how many weeks will the thrusters have to operate for the probe, initially at rest, to reach a velocity of 420 miles per minute [mi/min]? You may assume the initial velocity of the probe is zero miles per minute [0 mi/min].
Solution Summary: The author calculates the number of weeks the thrusters have to operate for the probe.
A space probe is built with a mass of 1700 pound-mass [lbm] before launch on Earth. The probe is powered by four ion thrusters, each capable of generating 225 millinewtons [mN] of thrust. Using Newton’s second law, the acceleration (a) of the craft is equal to the force (F) divided by the mass (m):
a
=
F
m
The velocity (v) of an object increases as an object accelerates. If the object starts at rest, the final velocity is given by the acceleration multiplied by the length of time the acceleration is applied to the object (t):
v
=
a
t
=
F
t
m
Using this equation, how many weeks will the thrusters have to operate for the probe, initially at rest, to reach a velocity of 420 miles per minute [mi/min]? You may assume the initial velocity of the probe is zero miles per minute [0 mi/min].
The gravitational constant g is 9.807 m/s² at sea level, but it decreases as you go up in elevation. A useful equation for this decrease
In g is g= a - bz, where z is the elevation
above sea level, a = 9.807 m/s², and b=3.32 x 10-61/s². An astronaut "weighs" 80.0 kg at sea level. [Technically this means that
his/her mass is 80.0 kg.] Calculate this person's weight in N while floating around in the International Space Station (z=325 km). If the
Space Station were to suddenly stop in its orbit, what gravitational acceleration would the astronaut feel Immediately after the satellite
stopped moving?
The person's weight in N while floating around in the International Space Station Is
The astronaut feels a gravitational acceleration of
m/s²
N.
1. Refrigerant R-22 with the mass of 2 kg is located inside the sealed container, initially saturated vapor at 6.8 bar. Heat was added to refrigerant and final pressure reached 20 bar according to pv=const. Neglecting the kinetic and potential energy changes determine:
Internal energy change in [J]
Heat added to the refrigerant in [J] and work done by fluid in [J].
3.draw the Temperature-volume diagram showing all stages.
4.What do you think about the final stage condition? Is it gas, liquid-gas, or liquid stage?
Use energy balance equation and find all unknowns using the NIST webbook.
A commonly used unit in everyday language to state weight is the pound (lb). There are actually several formal definitions of pound. One classification system defines a pound-mass (analogous to kg in SI units) and a pound-force (lbf) (analogous to a Newton); this is formally called English Engineering units but also commonly used in US Customary System units. The “pound” in the “pounds per square inch” of psi refers to pound-force. Hence, psi has units of force per area. Note that 1 lbf is defined as the gravitational force generated by 1 lb (mass) by multiplying it by the standard gravitational acceleration at the earth’s surface.
Starting with just the two everyday conversion approximations every Canadian should know (1.00 kg ≈ 2.20 lb (mass) and 1.00 inch ≈ 2.54 cm), derive an approximation of 1.00 psi in Pa through unit conversions only (show each step).
Chapter 8 Solutions
Thinking Like an Engineer: An Active Learning Approach (4th Edition)
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