Brake Power
Calculate the brake power (Watts) if the force applied at the end of the 3 m long brake arm is 250 N, and the rotation speed is 1100 rpm.
Expand Hint
Brake Power:
$$$\dot{W}_b=2\pi \tau \upsilon =2\pi FR\upsilon $$$
where
$$\tau$$
is torque,
$$\upsilon $$
is rotational speed,
$$F$$
is the force at the end of the brake arm, and
$$R$$
is the brake arm’s length.
Hint 2
Convert the rotational speed from rpm to rev/s:
$$$\upsilon =1100\: \frac{rev}{min}\cdot \frac{1\:min}{60\:secs}=18.33\:\frac{rev}{s}$$$
Brake Power:
$$$\dot{W}_b=2\pi \tau \upsilon =2\pi FR\upsilon $$$
where
$$\tau$$
is torque in
$$N \cdot m$$
,
$$\upsilon $$
is rotational speed in
$$rev/sec$$
,
$$F$$
is the force at the end of the brake arm, and
$$R$$
is the brake arm’s length. Thus,
$$$\tau = 250\:N\cdot 3\:m=750\:N\cdot m$$$
$$$\upsilon =1100\: \frac{rev}{min}\cdot \frac{1\:min}{60\:secs}=18.33\:\frac{rev}{s}$$$
Finally,
$$$\dot{W}_b=(2\pi )(750\:N\cdot m)(18.33\:\frac{rev}{s})=86,350\:W$$$
86,350 W
Time Analysis
See how quickly you looked at the hint, solution, and answer. This is important for making sure you will finish the FE Exam in time.- Hint: Not clicked
- Solution: Not clicked
- Answer: Not clicked
Similar Problems from FE Sub Section: Cycles and Processes
440. Rotational Speed
475. Brake Force
541. Friction Power
545. Indicated Power
Similar Problems from FE Section: HVAC
440. Rotational Speed
475. Brake Force
541. Friction Power
545. Indicated Power