Physics, 05.07.2019 21:20 Britney8394
It is known that the mass, m(t), of a radio-active substance decreases as it decays, and that the equation governing this is m′(t)=−0.015m(t) where t is in years. what is the half-life? (hint: find an exponential function which solves the equation. you will then have a formula for the mass, so you can find the half-life.)
Answers: 1
Physics, 21.06.2019 22:00
Aroll in a paper machine is powered by a separately excited dc machine. operating point 1 (under load): the roll typically operates at 764 rpm and must provide 301 nm of torque to oppose the load of the paper. the armature voltage is 230v for this operating point operating point 2 (no load): when the load is removed the speed of the roll increases to 900 rpm (the field characteristics are unchanged) la ea dev m (a) calculate the maximum torque (units of nm) that the motor can supply with this applied voltage (b) calculate the value of the armature resistance, ra (in ohms) (c) at operating point 1 (loaded condition), the field current, i, and the total input power (armature field), are measured to be to be 10 a and 28,600 w respectively. use this information to calculate the value of the field resistance, rf (in ohms). (d) (d) at operating point 1 (loaded condition), calculate the motor efficiency. express your answer as a percent to at least 2 significant digits. (d) if the field voltage is reduced by 1/2, calculate the new stall torque (in nm) of the motor (f). if the field voltage is reduced by 1/2, calculate the new no-load speed (in rad/sec)
Answers: 1
Physics, 21.06.2019 22:00
In 1980, alfa romeo introduced the first system to smooth a rough idle caused by ignition and camshaft timing changes.
Answers: 1
Physics, 22.06.2019 12:00
Asolid round steel rod 6.25 mm in diameter and 375 mm long is rigidly bonded to the end of solid square brass rod 25 mm on a side and 300 mm long. the geometric axes of the bare are along the same line. an axial tensile force of 5.4 kn is applied at the extreme ends of the assembly. for steel e = 200 gpa and for brass e = 90 gpa. determine the total elongation for the assembly.
Answers: 1
Physics, 22.06.2019 14:10
Amachinist turns the power on to a grinding wheel, at rest, at time t = 0 s. the wheel accelerates uniformly for 10 s and reaches the operating angular velocity of 96 rad/s. the wheel is run at that angular velocity for 40 s and then power is shut off. the wheel slows down uniformly at 1.5 rad/s2 until the wheel stops. in this situation, the time interval of deceleration is closest to:
Answers: 3
It is known that the mass, m(t), of a radio-active substance decreases as it decays, and that the eq...
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