Answer:
Electric field, 
Explanation:
It is given that,
Mass of sphere, m = 2.1 g = 0.0021 kg
Charge, 
We need to find the magnitude of electric field that balances the weight of a plastic spheres. So,

a = g



or

Hence, the magnitude of electric field that balances its weight is
. Hence, this is the required solution.
The correct option is SCALE.
This is because the experimental data you are interested in is mass and scale is the instrument that is used to measure mass. To use the scale, measure the mass of your water before you put it inside the sun and measure the mass again after you remove it from the sun. The difference in mass is the quantity of water that is evaporated.
There are different type of scale and the one that you use will depend on the size of the material that you want to measure.<span />
Answer:

Explanation:
The magnetic field strenght on the z-axis at a distance d from the center is,

Our values are:

Replacing,


Answer:

Explanation:
The exponential density function is given as


To find probability that bulb fails with the first 300hrs, we integrate from o to 300:


Hence probability of bulb failing within 300hrs is 25.92% or 0.2592
Mass m = 68 kg
center of gravity from his palms x = 0.7 m
center of gravity from his feet x ' = 1 m
forces exerted by the floor on his palms and feet are F and F ' respectively.
with respect to palms :---------------------
( F*0 ) - (W * x ) + [ F ' * (x+x') ] = 0
-mg*0.7 + F ' * 1.7 = 0 where W = weight = mg
F ' * 1.7 = mg * 0.7
F ' = mg * 0.7 / 1.7
= 68 *9.8 * ( 0.7 / 1.7 )
= 274.4 N
with respect to feet :--------------------
( F ' * 0 ) -( W* x ' ) + [F * ( x + x') ] = 0
-mg*1 + [ F * 1.7 ]= 0
F = mg / 1.7
= 392 N