Question

A force of ˆˆ ˆ 2i 3j 4k N + + acts on a body for 4 second, produces a displacement of ˆˆˆ (3i 4j 5k)m. + + The
power used is

Answer 1

Power is equal to work done by time work is equal to dot product of force displacement =6+12+20and it becomes 38 joule
power=work/time
power=38/4=9.5

Answer 2

The power used by the body is 9.5 watts.

Explanation:

Given that,

Force acting on the particle, $F=(2i+3j+4k)\ N$

Displacement of the particle, $d=(3i+4j+5k)\ m$

Time, t = 4 s

To find,

The power used by the body.

Solution,

The work done per unit time by an object is called power used by it. it is given by :

$P=\dfrac{W}{t}$

W is work done,

$W=F{\cdot} d$

$W=(2i+3j+4k){\cdot} (3i+4j+5k)$

$W=6+12+20=38\ J$

So,

$P=\dfrac{38\ J}{4\ s}$

P = 9.5 watts

So, the power used by the body is 9.5 watts. Hence, this is the required solution.

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Kinematics

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