D. Because the moons shadow during a total lunar eclipse is tinnier than the earth.
Answer:
Force=7.71KN in the opposite direction
Explanation:
Given the mass of the car(M)=1000Kg
The initial speed of the car(u)=100km/hr
we know that 1km/hr=5/18 m/sec
100km/hr=100*5/18 m/sec=27.77m/sec
the distance travelled before it stops (s)=50m
let the acceleration of the car be a
The final velocity of the car is 0.
we know that 

a=7.712m/
We know that F=Ma
F=1000* 7.712=7712N=7.71KN
Answer:
Explanation:
Given that,
A point charge is placed between two charges
Q1 = 4 μC
Q2 = -1 μC
Distance between the two charges is 1m
We want to find the point when the electric field will be zero.
Electric field can be calculated using
E = kQ/r²
Let the point charge be at a distance x from the first charge Q1, then, it will be at 1 -x from the second charge.
Then, the magnitude of the electric at point x is zero.
E = kQ1 / r² + kQ2 / r²
0 = kQ1 / x² - kQ2 / (1-x)²
kQ1 / x² = kQ2 / (1-x)²
Divide through by k
Q1 / x² = Q2 / (1-x)²
4μ / x² = 1μ / (1 - x)²
Divide through by μ
4 / x² = 1 / (1-x)²
Cross multiply
4(1-x)² = x²
4(1-2x+x²) = x²
4 - 8x + 4x² = x²
4x² - 8x + 4 - x² = 0
3x² - 8x + 4 = 0
Check attachment for solution of quadratic equation
We found that,
x = 2m or x = ⅔m
So, the electric field will be zero if placed ⅔m from point charge A, OR ⅓m from point charge B.
The time taken by the swimmer was 1 hour.
Why?
Since the swimmer is maintaining an angle of 150° while he was swimming, there were two components of the speed (horizontal and vertical). If we want to calculate the time taken by him to cross the river, we need to calculate the vertical speed and consider that the flow's speed is compensated by his horizontal speed.
We can calculate both components of the speed using the following formula:

Now, calculating we have:

Therefore, we have that the horizontal speed is compesating the flow's speed while his vertical speed is used to cross the river which is 1 Km wide.
Hence, we have that the tame taken is:

Have a nice day!
Answer:
78.4 m
Explanation:
To obtain the height of the cliff;
We can use the Relation to obtain the final velocity, v
v = u + at
a = acceleration due to gravity = 9.8m/s²
v = 0 + (9.8*4)
v = 0 + 39.2
v = 39.2 m/s
To obtain the Height, S
v² = u² + 2aS
39.2^2 = 0 + 2(9.8)S
39.2^2 = 0 + 19.6S
1536.64 = 19.6S
S = 1536.64 / 19.6
S = 78.4 m