Answer:
4.9 cm
Explanation:
From Hook's Law,
F = ke......................... Equation 1
Where F= force, e = extension, k = spring constant.
Note: the Force acting on the the spring is the weight of the mass.
W = mg.
F = mg.................... Equation 2
Where m = mass, g = acceleration due to gravity
Substitute equation 2 into equation 1
mg = ke
make e the subject of the equation
e = mg/k............... Equation 3.
Given: m = 2 kg, g = 9.8 m/s², k = 400 N/m
e = (2×9.8)/400
e = 19.6/400
e = 0.049 m
e = 4.9 cm
Answer:
A. 5.4 * 10^(-4) m
B. 500V
Explanation:
A. Electric potential, V is given as:
V = kq/r
This means that radius, r is
r = kq/V
r = (9 * 10^9 * 30 * 10^(-12))/500
r = (270 * 10^(-3))/500
r = 5.4 * 10^(-4) m
B. Now the radius is doubled and the charge is doubled,
V = (9 * 10^9 * 2 * 30 * 10^(-12))/(2 * 5.4 * 10^(-4) * 2)
V = 500V
Let
upthrust = T
weight = W = mg
Air resistance = F
When balloon is descending, air resistance acts upwards (positive)
By Newton's first law, the net force on the balloon is zero, or
T+F-W=0......................(1)
Let w=weight of material dumped so that balloon now travels upwards at constant speed.
Air resistance acts against motion, namely downwards.
The Newton's equation now reads
T-F-(W-w)=0................(2)
Subtract (2) from (1)
T+F-W - (T-F-(W-w)) = 0
Solve for w
w=2F, or
the WEIGHT of material to be released equals twice the resistance of air.
efficiency= [useful energy transferred ÷ total energy supply]×100%
So, [5500÷10000]×100%=0.55×100
=55%
Answer:
a. be sure to hold expansion cards by the edge connectors
Explanation:
Removal of loose jewelry is a good safety practice. Also not touching a microchip with a magnetized screwdriver is also a good practice.
But holding expansion cards by the edge connectors is not a good practice, so it is the odd one in the question. Therefore answer option a provides the correct and best answer to the question
