A 65-kg boy and a 45-kg girl use an elastic rope while engaged in a tug-of-war on an icy, frictionless surface

Question

Hey yall! sorry for the inconvenience, but i need help witht his for my physics activity.

A 65-kg boy and a 45-kg girl use an elastic rope while engaged in a tug-of-war on an icy, frictionless surface. If the acceleration of the girl toward the boy is 3.0m/s^2, find the magnitude of the acceleration of the boy towards the girl.

thanks guys :] !

Answer 1

The boy and the girl form an "internal system" so there is NO external forces involved -- because the surface is also frictionless. Picture 2 objects of different mass hanging on the ends of a massless rope with a pulley in the middle.

The rope is elastic so it is a spring. The force acting on the girl is equal to ma, ie 45*3 = 135 N.

By action and reaction, (or use Tension if you think in terms of an ordinary rope), this force in turn acts on the boy. It is important that the rope is massless, otherwise, the force will not "transmit" to the other end with the same value.

mass of boy x accel of boy = 135
65 * a = 135, ie, a = 2 m/s^2

Of course, the boy is moving TOWARD the girl as action and reaction pair

Answer 2

General Physics – 12. A 65 kg boy and a 45 kg girl use an elastic rope while engaged in a tug-of-war. Assume that they are on a

www.hhs.jordan.k12.ut.us/.../2nd%20Quarter/Force_Newton's

Answer 3

Are they using a lubricant?