The only thing in either one of those formulas that we don't know is the mass of the book.
Answer:
The tension on the string is
Explanation:
From the question we are told that
The mass of the rock is 
The density of the rock is
Generally the volume of the rock is mathematically evaluated as

substituting values


The volume of the rock immersed in water is
substituting values


mass of water been displaced by the this volume is
According to Archimedes principle
=> 

The weight of the water displace is



The actual weight of the rock is

The tension on the string is
substituting values
Answer:
Potential energy = 14.7 Joules.
Explanation:
Given the following data;
Mass, m = 1kg
Height, h = 1.5m
We know that acceleration due to gravity is equal to 9.8m/s²
Potential energy can be defined as an energy possessed by an object or body due to its position.
Mathematically, potential energy is given by the formula;

Where, P.E represents potential energy measured in Joules.
m represents the mass of an object.
g represents acceleration due to gravity measured in meters per seconds square.
h represents the height measured in meters.

Substituting into the equation, we have;

P.E = 14.7 Joules.
The North Magnetic Pole is the point on the surface of Earth's Northern Hemisphere at which the planet's magnetic field points vertically downwards (in other words, if a magnetic compass needle is allowed to rotate about a horizontal axis, it will point straight down). There is only one location where this occurs, near (but distinct from) the Geographic North Pole and the Geomagnetic North Pole. So yes true
Average velocity = (x( 2.08 ) - x ( 0 )) / ( 2.08 s - 0 s )
x ( 2.08 ) = 1.42 * 2.08² - 0.05 * 2.08³ =
= 1.42 * 4.3264 - 0.443456 = 6.143484 - 0.443456 ≈ 5.7 m
v = ( 5.7 m - 0 m) / (2.08 s - 0 s ) = 5.7 / 2.08 m/s = 27.4 m/s