(a) The free body of all the forces include, frictional force, weight of the box acting perpendicular and another acting parallel to the plane.
(b) When the box is sliding down, the frictional force acts towards the right.
(c) When the box slides up, the direction of the frictional force changes, it acts towards the left.
<h3>
Free body diagram</h3>
The free body diagram of all the forces on the box is obtained by noting the upward force and downward forces on the box as shown below;
/ W2
Ф → Ff
↓W1
where;
- Ff is the frictional force resisting the down motion of the box
- W1 is the perpendicular component of the box weight = Wcos(33)
- W2 is the parallel component of the box weight = Wsin(33)
(b) When the box is sliding down, the frictional force acts towards the right.
(c) When the box slides up, the direction of the frictional force changes, it acts towards the left.
Learn more about free body diagram of inclined objects here: brainly.com/question/4176810
Answer:
Explanation:
Given
Each student exert a force of 
Let mass of car be m
there are 18 students who lifts the car
Total force by 18 students 
therefore weight of car 
mass of car 

(b)
Answer:
true
Explanation:
Yes, it is true.
As the wattage is more than the prescribed wattage, it becomes overheated.
If you are given distance and a period of time, you can calculate
the speed. The velocity of an object is the rate of change of its position with
respect to a frame of reference, and is a function of time. Velocity is
equivalent to a specification of its speed and direction of motion (e.g. 60
km/h to the north).
Mid ocean ridges
The mountain ranges in the middle of the oceans
Sea floor spreading
The process by which new, oceanic crust forms along a mid ocean ridge and older crust moves away from the ridge. :)