The Weight of Spaceman Speff at the Surface of Planet

question 4

Multiple Choice

The weight of spaceman Speff at the surface of planet X, solely due to its gravitational pull, is 389 N. If he moves to a distance of 1.86 × 10⁴ km above the planet's surface, his weight changes to 24.31 N. What is the mass of planet X, if Speff's mass is 75.0 kg? (G = 6.67 × 10^-11 N ∙ m²/kg²)

• A) 2.99 × 10²⁴ kg
• B) 2.99 × 10¹⁸ kg
• C) 2.99 × 10¹⁷ kg
• D) 1.59 × 10¹⁸ kg

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Definitions:

Serotonin

A neurotransmitter in the brain that plays a significant role in mood regulation, sleep, and other physiological functions.

Agonists

Drugs that enhance a neurotransmitter’s activity.

Antidepressants

Medications designed to improve symptoms of depression by altering chemical balances in the brain.

Synaptic Reuptake

The presynaptic neuron’s process of reabsorbing its own neurotransmitters after signaling so that they can be released again the next time the neuron fires.