Answer:
The answer to your question is:
a) t = 3.81 s
b) vf = 37.4 m/s
Explanation:
Data
height = 71.3 m = 234 feet
t = 0 m/s
vf = ?
vo = 0 m/s
Formula
h = vot + 1/2gt²
vf = vo + gt
Process
a)
h = vot + 1/2gt²
71.3 = 0t + 1/2(9.81)t²
2(71.3) = 9,81t²
t² = 2(71.3)/9.81
t² = 14.53
t = 3.81 s
b)
vf = 0 + (9.81)(3.81)
vf = 37.4 m/s
Answer:
Force of <u>1</u><u>0</u><u>0</u><u> </u><u>N</u><u> </u>will be needed.
Explanation:

g is acceleration due to gravity
m is the mass

Answer:
The potential at the center of the sphere is -924 V
Explanation:
Given;
radius of the sphere, R = 0.22 m
electric field at the surface of the sphere, E = 4200 N/C
Since the electric field is directed towards the center of the sphere, the charge is negative.
The Potential is the same at every point in the sphere, and it is given as;
-------equation (1)
The electric field on the sphere is also given as;


Substitute in the value of q in equation (1)

Therefore, the potential at the center of the sphere is -924 V
Answer:
(i) the resistive force exerted by the sand on the bullet is - 1 x 10⁵ N
(ii) the time taken by the bullet to come to rest is 1 x 10⁻⁴ s
Explanation:
Given;
mass of bullet, m = 10 g = 0.01 kg
speed of the bullet, v = 10³ m/s
distance traveled by the bullet, d = 5 cm = 0.05 m
(i) the resistive force exerted by the sand on the bullet
the acceleration of the bullet is given by;
v² = u² + 2as
0 = (10³)² + a(2 x 0.05)
-0.1a = (10⁶)
-a = (10⁶) / 0.1
a = -1 x 10⁷ m/s²
The resistive force is given by;
F = ma
F = (0.01)(-1 x 10⁷)
F = - 1 x 10⁵ N
(ii) the time taken by the bullet to come to rest.
v = u + at
0 = 10³ + (-1 x 10⁷ t)
1 x 10⁷ t = 10³
t = 10³ / 10⁷
t = 1 x 10⁻⁴ s