00:05Question is, a particle moves with a velocity 6i-4j plus 3k meter per second under the influence
00:16of a constant force F is equal to 20i plus 15j minus 5k newton.
00:22Then the instantaneous power applied to the particle is a 35j per second, b 45j per second,
00:32c 25j per second, d 195j per second as we have to find the instantaneous power.
00:43In this condition, power is calculated by using formula P is equal to F dot V. So, power
00:55will be equal to is the force is given is 20i plus 15j minus 5k newton dot. The velocity
01:16is obtained is 6i minus 4j plus 3k meter per second. So, power will be obtained as, for
01:33simplification we will multiply the value of i with i, the value of j with j and the value
01:39of k with k. So, 20 into 6, it will be 120i dot i plus into minus, it will be
01:53minus 15 into
01:554, it will be 60 j dot j minus into plus, it will be minus 5 into 3, it will
02:05be 15 k dot k.
02:08As we know that i dot i is equal to j dot j is equal to k dot k is
02:15equal to 1. So, power will
02:19be obtained as 120 into 1 minus 60 into 1 minus 15 into 1. So, power will be obtained as
02:30120
02:32minus 60 minus 15. So, power will be obtained as 120 minus 60 minus 15, it will be minus 75.
02:45So, plus 120 minus 75. So, plus 120 minus 75, it will be plus 45 joule per second or watt.
03:06So, power
03:08is obtained as 45 joule per second or watt. So, the correct option will be B, 45 joule per second.
Comments