Answer to Question #256018 in Mechanics | Relativity for Leon Kennedy

Question

1.)A 20 – kilogram box of dog food is being pushed by an applied force and accelerates at 2 m/s2. A. Compute for its applied force if a frictional force of 50 N is acting in the opposite direction. B. Construct a free-body diagram to illustrate. 2.)A 2 – kilogram block of wood accelerates at 4 m/s2 along a rough road with a 10N force of friction acting in the opposite direction. a. Compute for the applied force needed. b. Construct a free-body diagram to illustrate. 3.) A van that is 1500 kg is moving with an initial velocity of 25 m/s in a time interval of 1.5 seconds before coming to a stop. Compute for the net force of the moving van. 4.)Gerard played golf with his friends. He hit the ball in a time interval of 0.0500 seconds with an applied force of 500 N. Compute for its impulse.

Answer 1

1) By Newton's second law:

$$ma=F-f,\\ F=ma+f=90\text{ N.}$$

2) Use the same law:

$$ma=F-f,\\ F=ma+f=18\text{ N.}$$

3) The same law:

$$F=ma=mv/t=25000\text{ N}.$$

4) The impulse is

$$I=Ft=25\text{ N}.$$