At the local playground, a 16-kg child sits on the end of a horizontal teeter-totter, 1.5 m from the pivot point. On the other side of the pivot an adult pushes straight down on the teeter-totter with a force of 95 N. In which direction does the teeter-totter rotate if the adult applies the force at a distance of (a) 3.0 m, (b) 2.5 m, or (c) 2.0 m from the pivot

Explanation:

a ) the weight of child creates a torque equal to = mg x L where m is mass of the child , L is distance from pivot

= 16 x 9.8 x 1.5

= 235.2 Nm

force applied by man  F = 95 N , distance from pivot = 3 m

torque = force x distance from pivot

95 x 3 = 285 Nm which is greater than the torque produced by child so

teeter-totter will tilt towards adult person

b ) in this case distance of force from pivot = 2.5

torque produced by it

= 95 x 2.5

= 237.5 Nm , this too is more . So this time too,  teeter-totter will tilt towards adult person

c ) in this case distance of force from pivot = 2.0

torque produced by it

= 95 x 2.0

= 190 Nm

which is less than the torque produced by child so

teeter-totter will tilt towards child .  

the independent variable, the one that is intentionally manipulated, is whether or not the car hits the barrier.

the dependent variable, the one that you measure the response in, is the distance that the washers travel.