First the velocity drops to zero in 1.2 secs. In those seconds it went upwards for 7.2 m, then it went from 87.2 to 0m. x-x0=v0*t+1/2*g*t^2 ergo t=sqrt(2x/g) that is 4.1761 s. Finally the total time required is 5.3761 s
The last one is correct (D)
The decimal point is placed after two digits starting from the end. For each decimal place, we can write the number divided by 100.
21.12 can be written as
.
Divide the numerator and denominator by 2:

The numerator and denominator can be divided by 2 again:

There is no other common factor between numerator and denominator other than 1. Hence, it is the reduced form.
Answer:
Yes is large enough
Explanation:
We need to apply the second Newton's Law to find the solution.
We know that,

And we know as well that

Replacing the aceleration value in the equation force we have,

Substituting our values we have,


The weight of the person is then,


<em>We can conclude that force on the ball is large to lift the ball</em>
Answer:
The charge on the dust particle is 
Explanation:
From the question we are told that
The length is 
The width is 
The charge is 
The mass suspended in mid-air is 
Generally the electric field on the carpet is mathematically represented as

Where
is the permittivity of free space with value 
substituting values


Generally the electric force keeping the dust particle on the air equal to the force of gravity acting on the particles

=> 
=> 
=> 
=> 