## 20191021

### Physics quiz question: camel spider translational kinetic energy (purported)

Physics 205A Quiz 4, fall semester 2019
Cuesta College, San Luis Obispo, CA

"Mr. Solifugae (probably Eremobates)"
Dallas Krentzel
flic.kr/p/9Ki3kX

Consider the myths listed below[*] as factual for camel spiders (Eremobates pallipes, also known as "wind scorpions"), which are native to California. Ignore friction and drag.
Camel spiders can reach up to 6 inches (15 cm) in length and weigh about 2 ounces (57 grams). Some common myths...are that they can run up to 30 mph (13 m/s) and jump up to 3 feet [1 m] high.
A camel spider that starts from rest and speeds up to 13 m/s will have an increase in translational kinetic energy of:
(A) 0.4 J.
(B) 0.6 J.
(C) 0.7 J.
(D) 5 J.

[*] Jessie Szalay, "Camel Spiders: Facts & Myths" (December 17, 2014), livescience.com/40025-camel-spiders-facts.html.

Correct answer (highlight to unhide): (D)

The change in translational kinetic energy is given by:

KEtr = (1/2)·m·(vf2v02),

KEtr = +4.8165 J,

or to two significant figures, the increase in translational kinetic energy is 5 J.

(Response (A) is (1/2)·m·(vfv0); response (B) is m·g·(yfy0); response (C) is m·(vfv0).)

Sections 70854, 70855
Exam code: quiz04JuR4
(A) : 11 students
(B) : 2 students
(C) : 1 student
(D) : 38 students

Success level: 73%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.56