The assembly consists of three titanium (Ti-6A1-4V) rods and a rigid bar AC. The cross-sectional area of each rod is given in the figure. If a force of 60 kip is applied to the ring F, determine the horizontal displacement of point F.
Ento 2010 Week 7 Notes February 22, 2016 o Order: Odonata Odous=tooth Common name: dragonflies, damselflies Species: 5,000 o Dragonflies & Damselflies Incomplete metamorphosis Biting mouthparts 2 pairs of wings VERY large eyes VERY small antennae Long abdomen Nymphs are aquatic Nymphs and adults are predators Considered beneficial Front and back wings beat independently o Damselfly vs. dragonfly Damselflies: are smaller than dragonflies hold wings straight back at rest o dragonflies hold wings out to side lay eggs in plant stems under water o dragonflies lay eggs on water surface o Note: Adults regulate their temperature Nymphs are predators “nymph” stage lasts for 1-3 years nymph to adult stage is dangerous must first pump hemolymph into its wings o Damselflies & Dragonflies: Hunt prey by sight Use leg hairs to catch prey Excellent fliers Muscles are attached to wings (like birds and bats) o Insect behavior : reaction of insects to specific conditions o Note: Males are territorial Mate in “wheel position” Male first removes rival sperm from female Male and female are in “tandem” during egg laying This keeps other males from mating with female February 24, 2016 o Order: Blattodea Blatta=cockroach Common name: cockroaches Species: 3,500 o Cockroaches Incomplete metamorphosis Chewing mouthparts 2 pairs of wings natural omnivores flattened bodies eggs laid in case=ootheca domestic pests o omnivore : eats both plants and animal material o cockroaches can be a nuisance in the kitchen o cockroaches are adapted to living with humans o only 20 cockroach species are pests o peripheral vision o antennae detect food and water keep antennae clean o tail hairs are sensitive to movement o cockroach Defense Against Pest Control “Bait” smell bait at a distance touch bait with antennae touch bait with hairs on mouthparts chew and taste bait cockroaches spread diseases (bacteria) mechanically! And they can cause allergies o Termites evolved from cockroaches: Cockroach fossils are around 300 million years old Some eat wood o Like termites, these cockroaches have protozoans to digest cellulose o Protozoans are passed on to baby cockroaches via feces Female cockroach “cares for young” by carrying ootheca o Cockroach reproduction Male strokes female antennae to identify her Male offers a food gift to her They mate end to end Females mate once and store sperm She can have 7 broods Ootheca has 40 eggs Nymphs burst ootheca by gulping air February 26,2016 o Order: Orthroptera Orthos=straight Ptera=wings Common name: grasshoppers, crickets, locusts 20,000 species o Grasshoppers/Crickets Incomplete metamorphosis Chewing mouthparts Front wings are narrow Back wings are fan-like Strong hind legs Males produce sound Sound receptors on leg/abdomen Oviposit eggs is soil or a plant Plant eaters Major agricultural pests o Stridulation: production of sound to attract a mate o Cricket songs: Each species is different More chirps/second=higher temperature Establish territory Call a female Warn others of predators o How is sound produced Crickets and some grasshoppers: Rub a wing against a wing Grasshoppers and locusts: Rub a leg against a wing Wings and legs have bumps and ridges= “file & scraper” Wings can serve as an amplifier o Crickets & Grasshoppers: “call” to find a mate mate at night to reduce danger from predators some predators and parasites are attracted to “call” it is safer to be a strong “silent” male o Cricket uses: Court case to lower rent China: raise crickets for fights Sell for fish bait A cricket genus=Gryllus o Locusts: #1 agricultural insect pest in the world 2 phases: solitary; gregarious stimulation of hairs on back legs of solitary locusts causes swarming: solitary locusts-----> gregarious locusts swarm may cover 500 square miles and have 50 billion insects! “nymphs” stay in soil several years during a drought “blew/flew” to the Americas from Africa o Locust swarms in Africa: Eat: 2,000 tons/day Travel: 65 miles/day Oviposit in soil 1 female-500 nymphs o Locusts have plagued us since biblical times Exodus Chapter 10: “I will bring locusts into your country…and they shall fill your houses…”