Answer:
speed is the rate of change in distance thus it is scalar physical quantity
while velocity is the rate of change in displacement thus it is a vector physical quantity
Explanation:
vector physical quantity: is a quantity that requires both magnitude and direction to identify
scalar quantity: requires only magnitude to identify.
maximum allowed value of the speed in roller coaster is given as

now from kinematics we can say

here initial speed will be

acceleration is due to gravity

now we can use this to find the height



so maximum allowed height will be 20.4 m
In a fluid, all the forces exerted by the individual particles combine to make up the pressure exerted by the fluid
Due to fundamental nature of fluids, a fluid cannot remain at rest under the presence of shear stress. However, fluids can exert pressure normal to any contacting surface. If a point in the fluid is thought of as a small cube, then it follows from the principles of equilibrium that the pressure on every side of this unit of fluid must be equal. but if this were not a case, the fluid would move in the directions of the resulting force, So the pressure on a fluid at rest is isotropic.
Hope This Helps :D <span />
The point obviously is in the 3rs quadrant
So
စ= tan^-1( y/x)-180
စ= -89.7°