Question

Homework Set #7 How long must a force of 5.00 N act on a block of 3.00-kg mass in order to give it a velocity of 4.00 m/s? 1. 2. A force of 25.0 N acts on a 10.0-kg mass in the positive x-direction, while another force of 13.5 N acts in the negative x-direction. If the mass is initially at rest, find (a) the time rate of change of momentum, (b) the change in momentum after 1.85 s, and (c)the velocity of the mass at the end of 1.85 s 3. A baseball traveling at 150 km/hr is struck by a bat and goes straight back to the pitcher at the same speed. If the baseball has a mass of 200 g, find (a) the change in the momentum of the baseball, (b) the impulse imparted to the ball, and (c) the average force acting if the bat was in contact with the ball for 0.1s.

need help with #1, #2, #3 please. Thank you

Answer 1

Let's say the time required is = t(s) mass m = 3 kg Force = 5 N acceleration = a =? Velocity v = 4.00 m/s as form newton's second law of motion Force = ma Rightarrow a = Force/m = 5/3 m/s^2 Assumining that the block was initially at rest Rightarrow v_0 = 0 m/s applying first equation of mortion v = v_0 + at Rightarrow t = v_v_0/a = 4-0/(5/3) = 12/5 t = 2.4 seconds rightarrow