Question #10e47

2 Answers
Jan 18, 2018

Toque applied = 6 N.m6N.m & power is about120120 watt

Explanation:

Here,by applying the torque angular retardation was done to stop its motion(considering no skidding was there).

so, angular retardation= alphaα = change in angular velocity i.e omega/tωt = 40/104010 i.e 44 radian/s^2s2

Now, torque = IalphaIα (where, I is the moment of inertia)

moment of inertia of a cylinder passing through its axis is (Mr^2)/2Mr22 =1.5 Kg.m^21.5Kg.m2

so. tauτ = 1.5*4 N.m1.54N.m i,e 6 N.m6N.m

so,angular power required = (tau* theta)/tτθt i.e about 120120 watt(tau*thetaτθ= work done,dividing by time required for this angular displacement of thetaθ by the time tt in which it was brought to rest due to application of this torque) ( thetaθ is angular displacement)( theta = (omega)^2/(2 alpha)=(40^2)/(2*4)=200 radianθ=(ω)22α=40224=200radian)

Jan 18, 2018

The torque is =6Nm=6Nm. The power is =240W=240W

Explanation:

The torque and the angular acceleration are related

"Torque (Nm)"="Moment of inertia (kgm^2)"xx "angular acceleration (rads^-2)"Torque (Nm)=Moment of inertia (kgm^2)×angular acceleration (rads^-2)

tau=Ixxalphaτ=I×α

The moment of inertia of the solid cylinder is

I=(mr^2)/2I=mr22

The mass of the cylinder is m=3kgm=3kg

The radius of the cylinder is r=1.0mr=1.0m

The moment of inertia is I=(3xx1^2)/2=1.5kgm^2I=3×122=1.5kgm2

The initial angular velocity is omega_0=40rads^-1ω0=40rads1

The final angular velocity is omega_1=0rads^-1ω1=0rads1

The time is t=10st=10s

Apply the equation (to find the angular acceleration (alpha)(α))

omega_1=omega_0+alphatω1=ω0+αt

alpha=(omega_1-omega_0)/t=(0-40)/10=-4rads^-2α=ω1ω0t=04010=4rads2

The torque to be applied is

tau=Ialpha=1.5xx4=6Nmτ=Iα=1.5×4=6Nm

"Power (W)"= "torque (Nm)"xx "angular velocity (rads^-1)"Power (W)=torque (Nm)×angular velocity (rads^-1)

P=tauxx omega_0P=τ×ω0

The power is P=6xx40=240WP=6×40=240W