A strength and conditioning coach recommends that an athlete train by pulling a large amount of mass while sprinting. If action-reaction forces are always equal and opposite, which explanation best describes the action reaction pair acting on the runner ? A) The runner will not move because the applied force exerted by the runner on the mass will create an equal and opposite frictional force, canceling the applied force
B) The runner will accelerate forward because the applied force exerted by the runner creates an equal and opposite frictional force by the ground, but these forces are exerted on different objects.
С) The runner will accelerate forward because the force of friction by the mass on the runner is always less than the applied force by the runner, resulting in a net force forward
D) The runner will remain motionless because the applied force by the runner in the forward direction is less than the frictional force from the ground, acting in the opposite direction.

The correct answer is B)

Explanation:

Solution:

The correct answer is B)

Because,  

Runner is applying a force and forwarding ahead which creates equal and opposite frictional force by the ground. But key point here is that, the equal and opposite force is acting on different objects not on the runner. As, friction force will be applied to the heavy mass and the runner by the ground. So, Runner will always apply greater and opposite force than the total friction force that he is experiencing because of heavy mass friction and its friction due to ground in order to move ahead.

For example, if you pull a empty cart with equal and opposite force, then the cart will not move, as the net force is zero. So, in order to move the cart. you have to apply greater and opposite force.

the answer is b, have negligible mass

dec 23, 2016 - a load of bricks weighing 680 n a distance of 10 m across a parking lot. if if the worker pushes the cart with a constant force of 209 n, what work= force x distance = 220 n x 10 m = 2200 n.m = 2200 j i don't know where the person got it from, but the initial part, work= force x distance me.