Question

attraction if the distance between these two masses is halved? Energy and Oscillations 4 A force of 8O N used to push a table across a room does 800 J of wok. How far the chair move in this process? S. A net force of 60 N accelerates a 5.0 kg mass over a distance of 10 m. What is the work done by this net force? a. b. What is the increase in kinetic energy of the mass? 6- A 2.0 kg ball has a velocity of 5.0 m/s. a. What is the kinetic energy of the ball? b. How much work would be required to stop this ball? 7- A box with a mass of 4.0 kg is lifted through a height of 3.0 m in order to place it upon the shelf or a closet. a. What is the increase in potential energy of the box? b. How much work was required to lift the box to this position? The behavior of fluids

Answer 1

force = 80 N, workdone = 800J W = F.s = W/f = s s = 800j/ 80n = 10m thus distance moved s = 10m F = 60N, m = 5kg, s = 10m a = F/m = 60n/5 kg = 12 m/s^2 v = u^2+ 2as = 2 times (12 m/s^2) times (10m) = 240 m/s^2 changing kinetic energy = 1/2 mv^2 = 1.2 times (5kg)(240 m/s^2) K.E = 600 J work done = W = force times distance = F_net times s W = (60N)(10m) = 600J workdone is converted into kinetic energy m = 2.0kg v = 5 m/s K.E = 1/2 mv^2 = 1.2 times 2.0 kg times 25 m/s^2 = 25 J as the kinetic energy is 25J thus a work of 25J should be done in opposite direction m = 4.0kg h = 3.0 m, g = 9.81 m/s^2 P.E = (4kg)(9.8 m/s^2) = 117.65 work done = change in potential energy W = 117.6J