A 20 Kg Uniform Door Has a Width of 1

question 20

Multiple Choice

A 20 kg uniform door has a width of 1.2 m and a height of 2.5 m. The door is mounted on a post by a pair of hinges, marked 1 and 2, at the top and bottom of the door. An external force of 60 N, at an angle of 30° above the horizontal, is applied to the doorknob, as shown. The doorknob is 1.0 m above the bottom of the door.
-In the figure,the sum of the y-components of the forces,exerted on the door by hinges 1 and 2,is closest to:

• A)145 N
• B)165 N
• C)195 N
• D)225 N
• E)250 N

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Definitions:

Correlational Studies

Studies in which the investigator analyzes the relationships among variables that were in place before the study, without manipulating those variables.

Placebo Effects

Observable or measurable changes in health or behavior resulting from the administration of a placebo, demonstrating the power of belief and expectation in the healing process.

Double-blind

A study design in which neither the participants nor the experimenters know who is receiving a particular treatment, to prevent bias in the results.

Attention Deficit Disorder

A mental health disorder characterized by a persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development.