Answer:
Explanation:
The energy stored in the spring is used to throw the ball upwards . Let the height reached be h
stored energy of spring = 1/2 k y² , k is spring constant and y is compression created in the spring
stored energy of spring = potential energy of the ball
1/2 k y² = mgh , m is mass of the ball , h is height attained by ball
.5 k x .055² = .025 x 2.84
.0015125 k = .071
k = .071 / .0015125
= 46.9 N / m .
Answer:
V1 =8.1 m/s
Explanation:
height at highest point (h2) = 4.1 m
height at lowest point (h1) = 0.8 m
acceleration due to gravity (g) = 9.8 m/s^{2}
from conservation of energy, the total energy at the lowest point will be the same as the total energy at the highest point. therefore
mgh1 +
= mgh2 + 
where
- speed at highest point = V2
- speed at lowest point = V1
- mass of the girl and swing = m
- at the highest point, the speed is minimum (V1 = 0)
- at the lowest point the speed is maximum (V2 is the maximum speed)
- therefore the equation becomes mgh1 +
= mgh2
m(gh1 +
) = m(gh2)
gh1 +
= gh2
V1 = 
now we can substitute all required values into the equation above.
V1 = 
V1 = 
V1 =8.1 m/s
Answer:
Speed of the electron will be 
Explanation:
We have given that charge on electron 
Mass of electron 
Potential difference = 
Now according to energy conservation 


Answer:
Option B
Explanation:
The phase difference is found by subtracting the 2.3m for the receiver from the other speaker which is 2.9m hence
Phase difference= 2.9-2.3= 0.6
Let
be the direction the swimmer must swim relative to east. Then her velocity relative to the water is

The current has velocity vector (relative to the Earth)

The swimmer's resultant velocity (her velocity relative to the Earth) is then


We want the resultant vector to be pointing straight north, which means its horizontal component must be 0:

which is approximately 41º west of north.