Answer:
Electric field magnitude
E = K/qd
Where
K = kinetic energy of electron
d = electron distance
q = charge
Explanation:
Given the relationship between workdone and energy
Work-energy theorem:
Net workdone = Energy change
W = ∆E
In this case
W = ∆K.E
And,
∆K.E = K(final) - K(initial)
To stop the kinetic energy | K(final) = 0
K(initial) = K (given)
∆K.E = 0 - K = -K
Let the electric force on the electron has magnitude F.
And
W = -Fd = ∆K.E = -K
-Fd = -K
F = K/d .....1
The magnitude of the electric field E that can stop these electron in a distance d:
E = F/q ......2
Where q is the charge on electron.
substituting equation 1 to 2
E = (K/d)/q = K/qd
E = K/qd
Answer:
(a) 5.7 s
(b) 39 m/s
Explanation:
(a) u = 18 m/s
At the maximum height, the final velocity of ball is zero. lte teh time taken by the ball to go from 50 m height to maximum height is t.
use first equation of motion.
v = u + g t
0 = 18 - 10 x t
t = 1.8 s
Let the maximum height attained by the ball when it thrown from 50 m height is h'.
Use third equation of motion
v^2 = u^2 + 2 g h'
0 = 18^2 - 2 x 10 x h'
h' = 16.2 m
Total height from the ground H = h + h' = 50 + 16.2 = 76.2 m
Let t' be the time taken by the ball to hit the ground as it falls from maximum height.
use third equation of motion
H = ut + 1/2 x g t'^2
76.2 = 0 + 1/2 x 10 x t'^2
t' = 3.9 s
Total time taken by the ball to hit the ground = T = t + t' = 1.8 + 3.9 = 5.7 s
(b) Let v be the velocity with which the ball strikes the ground.
v^2 = u^2 + 2 g H
v^2 = 0 + 2 x 10 x 76.2
v = 39 m/s
<h2>Hello!</h2>
The answer is: B. Kinetic energy
<h2>
Why?</h2>
Since the ball is falling, speed increases because the gravity acceleration is acting. When speed increases, the kinetic energy increases too, so the ball is gaining kinetic energy.
The gravity acceleration is equal to 
, it means that when falling, the ball will increase it's speed 9.81m every second.
We can calculate the kinetic energy by using the following formula:
Where:
Have a nice day!
<h2 />
Answer: 2kg
Explanation:
This problem is a textbook conservation of momentum problem. The intial momentum is equal to the final momentum. For the initial state of each block, only the first one was moving. Then they both combine to move together.
Pi = Pf
with p = mv
(6kg)*(4m/s) = (6kg+xkg)(3m/s)
Let x equal the unknown mass of block 2
24 = 18 + 3x
6 = 3x
x = 2kg
