You are pushing a wooden crate across the floor at constant speed. you decide to turn the crate on end, reducing by half the surface area in contact with the floor. in the new orientation, to push the same crate across the same floor with the same speed, the force that you apply must be abouta. four times as greatb. twice as greatc. equally greatd. half as greate. one-fourth as greatas the force required before you changed the crate's orientation.

D. Half as great

Explanation:

Since we know that the friction force between the surface of crate and ground is given as

so here we know that

= friction coefficient between two surfaces which depends on the effective contact area between two surfaces

= normal force due to the object

So when we turn the object on another side such that the surface area is half then the friction coefficient will become also half

So here the friction force will also reduce to half

so correct answer will be

D. Half as great

heat the gas and measure the pressure