Question

Which of the following are equivalent units?
A) a watt and a joule
B) a newton-meter and a joule
C )a newton and a joule/sec
D) a watt and a newton

Answer 1

Answer : The correct options are, (B) a newton-meter and a joule and (C)  a newton and a joule/sec

Explanation :

As we know that,

$1N=1Kg\text{ m }s^{-2}\\\\1J=1\text{Kg }m^2s^{-2}\\\\1W=1\text{Kg }m^2s^{-3}$

or we can say that,

$1W=1J/s\\\\1J=1Nm\\\\1N=1J/s\\\\1W=1Nms^{-1}$

From the given options, the option B and C are the equivalent units.

Hence, the correct options are, (B) and (C)

Answer 2

Answer: B) a newton-meter and a joule

Explanation:

Joule is the unit if energy. One joule is equal to one Newton-meter.

1 J = 1 N-m

Energy is equivalent to work done which is equal to dot product of force and displacement.

E = W = F.s

Energy is measured in Joules. Force is measured in Newtons and displacement is measured in meters.

1 Joule = 1 kg m²/s²

1 N = 1 kg m/s²

1 N-m = 1 kg m/s² × m = 1 kg m²/s² = 1 J