Answer:
Because the uncontrolled and unreasonable use of energy resources in the past few decades has led to the depletion of conventional type of resources. Although, measures are taken at the government levels to control the energy consumption, these attempts only meet with little success. Public awareness is the only way to successfully deal with this problem.
Explanation:
We will first record its mass and then its volume by measuring its dimensions
then divide mass by volume and will get density of regular solid
First do 1.6 m (how far he jumps) 9.8 m/s (what gravity is measured at) then times 2
= 31.36
Sq root = 5.6
Answer:

Explanation:
information we know:
Total force: 
Weight: 
distance: 
vertical component of the force: 
-------------
In this case we need the formulas to calculate the components of the force (because to calculate the work we need the horizontal component of the force).
horizontal component: 
vertical component: 
but from the given information we know that 
so, equation these two
and 

and we know the force
, thus:

now we clear for 

the angle to the horizontal is 15.466°, with this information we can calculate the horizontal component of the force:


whith this horizontal component we calculate the work to move the crate a distance of 4 m:

the work done is W=173.48J