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A woodpecker's brain is specially protected from large decelerations by tendon-like attachments inside the skull. While pecking on a tree, the woodpecker's head comes to a stop from an initial velocity of 0.600 m/s in a distance of only 2.00 mm. (a) Find the acceleration in
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College Physics
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- A Formula One car is a single-seat racing car with an open cockpit and substantial wings located in the front and rear. At high speeds, the aerodynamics of the car help to create a strong downward force which allows the car to brake from 27.8 m/s (100 km/hr or 62.2 mi/hr) to 0 in as small of a distance as 17 meters. Determine the deceleration rate (i.e., acceleration) achieved by such a car.arrow_forwardAn indestructible bullet 2.00 cm long is fired straight through a board that is 10.0 cm thick. The bullet strikes the board with a speed of 470 m/s and emerges with aspeed of 265 m/s. (To simplify, assume that the bullet accelerates only while the front tip is in contact with the wood.) (a) What is the average acceleration of the bullet through the board? m/s2 (b) What is the total time that the bullet is in contact with the board? (Enter the total time for the bullet to completely emerge from the board.)arrow_forwardA car weighing 2.5 metric tons and traveling at 90 km/h hits a 500 m long stretch of black ice. Unfortunately, due to skidding, neither accelerating nor braking has any effect on the speed! The driver manages to maintain steady straight direction of motion and the only impact is provided by the ice friction force, which is numerically equal to 4v² Newtons, where the velocity v of the car is measured in m/sec. (a) Using Newton's Second Law F = ma, set up a mathematical model for the position x(t) and velocity v(t) of the car as functions of time t. Start by drawing a diagram and choosing a consistent system of units based on kg, m, sec (1 ton = 1000 kg, 1 m/sec = 3.6 km/h, 1 N = 1 kg · m/sec²). Introduce and label the variables, show the units and write down the differential equations and the intial conditions. (b) Use the model in part a to calculate v(t) and x(t). Fully show the process of solving the initial value problems. (c) Based on your work so far, how long will it take to pass…arrow_forward
- A basketball player jumps straight up for a ball. To do this, he lowers his body 0.330 m and then accelerates through this distance by forcefully straightening his legs. This player leaves the floor with a vertical velocity sufficient to carry him 0.920 m above the floor. (a) Calculate his velocity (in m/s) when he leaves the floor. (Enter a number.) m/s (b) Calculate his acceleration (in m/s2) while he is straightening his legs. He goes from zero to the velocity found in part (a) in a distance of 0.330 m. (Enter a number.) m/s² (c) Calculate the force (in N) he exerts on the floor to do this, given that his mass is 102 kg. (Enter a number.) Narrow_forwardThe acceleration of an object is given by a = 3.0 t2 -2.0 t +1.0 (m / s2). Determine the velocity at t = 2.0 s. The initial velocity v0 = 2.0 m / s. (Hint: a = dv / dt or dv = a dt, use the concept of integration)arrow_forwardA 68 kg man drops to a concrete patio from a window 0.45 m above the patio. He neglects to bend his knees on landing, taking 2.4 cm to stop. (a) What is his average acceleration from when his feet first touch the patio to when he stops?(b) What is the magnitude of the average stopping force exerted on him by the patio?arrow_forward
- A basketball player jumps straight up for a ball. To do this, he lowers his body 0.340 m and then accelerates through this distance by forcefully straightening his legs. This player leaves the floor with a vertical velocity sufficient to carry him 0.880 m above the floor. (a) Calculate his velocity (in m/s) when he leaves the floor. (b) Calculate his acceleration (in m/s2) while he is straightening his legs. He goes from zero to the velocity found in part (a) in a distance of 0.340 m. (c) Calculate the force (in N) he exerts on the floor to do this, given that his mass is 120 kg.arrow_forwardAcceleration is sometimes expressed in multiples of g, where g = 9.8 m/s^2 is the acceleration due to the earth's gravity. In a car crash, the car's velocity may go from 31 m/s to 0.0 m/s in 0.15 s. How many g's are experienced, on average, by the driver?arrow_forwardYou are designing a high-speed elevator for a new skyscraper. The elevator will have a mass limit of 2400 kg (including passengers). For passenger comfort, you choose the maximum ascent speed to be 18.0 m/s, the maximum descent speed to be 10.0 m/s, and the maximum acceleration magnitude to be 3.30 m/s2. Ignore friction. (a)What is the minimum time it will take the elevator to ascend from the lobby to the observation deck, a vertical displacement of 640 m? (b)What is the maximum value of a 60.0-kg passenger’s apparent weight during the ascent?arrow_forward
- The head injury criterion (HIC) is used to assess the likelihood of head injuries arising from various types of collisions; an HIC greater than about 1000 s is likely to result in severe injuries or even death. The criterion can be written as HIC=(aavg/g)^2.5Δt, where aavg is the average acceleration during the time Δt that the head is being accelerated, and g is the free-fall acceleration. The figure shows a simplified graph of the net force on a crash dummy's 4.5 kg head as it hits the airbag during a automobile collision. What is the HIC in this collision? Give your answer in seconds.arrow_forwardA basketball player jumps straight up for a ball. To do this, he lowers his body 0.310 m and then accelerates through this distance by forcefully straightening his legs. This player leaves the floor with a vertical velocity sufficient to carry him 0.980 m above the floor. (a) Calculate his velocity (in m/s) when he leaves the floor. (Enter a number.) m/s (b) Calculate his acceleration (in m/s2) while he is straightening his legs. He goes from zero to the velocity found in part (a) in a distance of 0.310 m. (Enter a number.) m/s² (c) Calculate the force (in N) he exerts on the floor to do this, given that his mass is 102 kg. (Enter a number.) N + Submit Answerarrow_forward(a) The velocity of a particle changes from v = 2î + 5ĵ -3k m/s to V2= 5î - 7j+ 2k m/s in 2 s. What is its average acceleration? (b) A particle has an acceleration of a = -7î + 3ĵ m/s² for a period of 4 s. After this time the velocity is V2 = 6î - 2k m/s. What was the initial velocity?arrow_forward
- Glencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-Hill