**What do you mean by newton-meter (Nm)?**

Difficulty: Hard

**SI unit of torque is newton-meter (Nm).**

**Newton-meter (Nm):**

A torque of 1 N m is caused by a force of 1 N acting perpendicular to the moment arm 1 m long.

**Mini Exercise**

A force of 150 N can loosen a nut when applied at the end of a spanner 10 cm long.

**Solution:**

F = 150 N

$L = 10 cm=\frac{10}{100}=0.1m$

Torque Τ = F × L

= 150 \: N\times 0.1m

= 15 Nm

**1. What should be the length of the spanner to loosen the same nut with a 60 N force?**

**Solution: **

F = 60 N

Τ = 15 Nm

L = ?

$L = \frac{T}{F}$

$L = \frac{15}{60}$

= 0.25 m

**2. How much force would be sufficient to loosen it with a 6 cm long spanner?**

**Solution:**

L = 6 cm = $\frac{6}{100}=0.06m$

Τ = 15 Nm

F =?

F= $\frac{T}{L}$

F= $\frac{15}{0.06}=250N$

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