[单选题]
An object's angular moh-8zz4luk uvzz( f ..u(xfi)amentum cha emm6 un)2cah4ji6xo1l4l 8xmnges by $20 \; kgm^{2}/s$ in 4.0 s. What magnitude average torque acted on this object?
A. $2.5 \; N \cdot m$
B. $5.0 \; N \cdot m$
C. $40 \; N \cdot m$
D. $80 \; N \cdot m$
Post time 2024-1-22 02:51:16