Answer:
Vr = 20 [km/h]
Explanation:
In order to solve this problem, we have to add the relative velocities. We must remember that velocity is a vector, therefore it has magnitude and direction. We will take the sea as the reference measurement level.
Let's take the direction of the ship as positive. Therefore the boy moves in the opposite direction (Negative) to the reference level (the sea).
Answer:
Explanation:
Given
Length of plank is 1.6 m
Force is applied on the left side of plank
Force is applied 43 cm from the left end O.
Mass of the plank is
for equilibrium
Net torque must be zero. Taking torque about left side of the plank
Net vertical force must be zero on the plank
Answer
Any force greater 490N
Explanation
The force required just to make an object slide over a rough horizontal surface is any force greater that the static friction which given by;
Given;
Hence;
F = 0.5 x 100 x 9.8
F = 490N.
We will only need the coefficient of kinetic friction if we were asked to find the force required to keep the object moving uniformly. Usually, the force needed to keep an object moving uniformly over a rough surface is lesser that which is needed to start its motion.
In this problem, we were only asked to find the minimum force required to make the object move which we have done.