A mass of 2 kg stretches a spring 0.07 m. The mass is in a medium that exerts a viscous resistance of 23 N when the mass has a velocity of 2 The viscous resistance is proportional to the speed of the object. m - S Suppose the object is displaced an additional 0.03 m and released. m Find an function to express the object's displacement from the spring's natural position, in m after t seconds. Let positive displacements indicate a stretched spring, and use 9.8 gravity. as the acceleration due to $2 u(t) = Submit Question

Find the constant of proportionality. E varies jointly with I and R. If R=25 and I=5, then E=125.

Skidding in a Curve A car is traveling on a curve that forms a circular arc. The force F needed to keep the car from skidding is jointly proportional to the weight w of the car and the square of its speed s and is inversely proportional to the radius r of the curve. a Write an equation that expresses this variation. b A car weighing 1600 lb travels around a curve at 60 mi/h. The next car to round this curve weighs 2500 lb and requires the same force as the first car to keep from skidding. How fast is the second car traveling?

In Example 7, find the average speed of the car (a) from t1=0tot2=1 second and (b) from t1=1 second to t2=4 seconds.

Computer Virus The number V of computers infected by a virus increases according to the model Vt=100e4.6052t, where t is the time in hours. Find the number of computers infected after (a) 1 hour, (b) 1.5 hours, and (c) 2 hours.