Question

If $\vec F$=(60$\hat i$+15$\hat j$-3$\hat k$)N and $\vec V$=(2$\hat i$-4$\hat j$+5$\hat k$)m/s, then instantaneous power is:

• A. 195 watt
• B. 45 watt
• C. 75 watt
• D. 100 watt

Answer 1

Answer: (B)

45 watt

Answer 2

P=$\vec F$.$\vec V$
=(60$\hat i$+15$\hat j$-3$\hat k$).(2$\hat i$-4$\hat j$+5$\hat k$)
=(120-60-15)=45 watt