Question 202: Laws of Motion

Question

A door $$1.2 \mathrm{~m}$$ wide requires a force of $$1 \mathrm{~N}$$ to be applied perpendicular at the free end to open or close it. The perpendicular force required at a point $$0.2 \mathrm{~m}$$ distant from the hinges for opening or closing the door is

Accepted Answer

To open or close the door, a force of $$1 \mathrm{~N}$$ is applied at a distance of $$1.2 \mathrm{~m}$$ from the hinges.
Moment of the force $$=\mathrm{F} 	imes \mathrm{d}=1 	imes 1.2=1.2 \mathrm{~N}-\mathrm{m}$$
When the force is applied at $$\mathrm{P}$$ at a distance of $$0.2 \mathrm{~m}$$ from $$\mathrm{O}$$, then the force required to have the same moment is given by
$$1.2=\mathrm{F} 	imes 0.2 \quad 	herefore \mathrm{F}=\frac{1.2}{0.2}=6 \mathrm{~N}$$

Answer

3.6 N

Answer

2.4 N

Answer

1.2 N

Answer

6.0 N

Laws of Motion

A door $1.2 \mathrm{~m} wide requires a force of 1 \mathrm{~N} to be applied perpendicular at the free end to open or close it. The perpendicular force required at a point 0.2 \mathrm{~m}$ distant from the hinges for opening or closing the door is

Choose the correct answer: