2. a 20 gram bullet exits the rifle at a speed of 985 m/s. the gun barrel is 0.8 m long. What was the force during the firing. 3. A force of 380 N is applied to a 38 kg object over a distance of 2.5 meters. What is the speed
of the object after it accelerates?
4. A 21,000 kg train is traveling at 21 m/s. It accelerates as it enters a tunnel because of a constant force of 45,000 N from the engine. The train is in the tunnel for 5.25 seconds. What is the final speed of the train?

When the displacement of a mass on a spring is 12a the half of the amplitude, what fraction of the mechanical energy is kinetic energy? at what displacement, as a fraction of a, is the mechanical energy half kinetic and half potential?

Large electric fields in cell membranes cause ions to move through the cell wall. the field strength in a typical membrane is 1.0 x 10 7 n/c. what is the magnitude of the force on a calcium ion with charge +e? what is its acceleration? is it possible for a particle with the same charge as as calcium to have a different acceleration if placed at this location? what would change the acceleration: mass of the particle? diameter of the particle?

Select the best definition for wavelength. the height of an oscillating electromagnetic wave the rate at which electromagnetic waves oscillate. the distance between two crests of an electromagnetic wave. the oscillations of electric and magnetic fields select the best definition for frequency. the oscillations of electric and magnetic fields. the height of an oscillating electromagnetic wave. the distance between two crests of an electromagnetic wave. the rate at which electromagnetic waves oscillate