Question

i need help solving all 4 of these

6. Consider a crate that is being pulled up a frictionless inclined plane at a constant speed, as shown in the figure. The work done by the tension in the cable on the crate is a. positive b. zero. c. negative. d. Need more information. Frict 7. Consider a crate that is being pulled up a frictionless inclined plane at a constant speed, as shown in the figure. The work done by the To normal force on the crate is a. positive. b. zero. c. negative. d. Need more information 8. Consider a crate that is being pulled up a frictionless inclined plane at a constant speed, as shown in the figure. The work done by the force of gravity on the crate is a. positive. b. zero. C. negative. d. Need more information. 9. Spike, our tenacious young lad from the first exam, is frictionless slide shopping with his parental units and is trying to decide between the four slides shown in the figure below. Assuming that he wants to pick the design which will give him the greatest possible speed when he reaches the bottom, which one should he pick? a. Slide A b. Slide B c. Slide C d. Slide D e. It doesn't matter, his speed would be the same for each slide.

Answer 1

Mathematically Workdone is expressed as,

W F.d.cose

Where,

F is the Force

d is the displacement and

$\theta$ is the angle between force and displacement

1) when force and displacement are perpendicular to each other or when either force or displacement is zero then the  work done is said to be zero work

2) the work done on an object is said to be positive work when force and displacement are in same direction.

3) The work done is said to be negative work when force and displacement are in opposite direction.

For Question 6.

d

In question 6 Tension (Force) in the cable and displacement are in same direction therefore workdone is positive

For Question 7.

р N

In question 7 Normal Force on the crate and displacement are perpendicular to each other therefore workdone is Zero.

For Question 8.

d 0 Mg

In this case angle between gravitational force and displacement is more than 90 degree and value of cos$\theta$ for this angle is negative therefore workdone is Negative.