Answer:
The net charge is 
Solution:
As per the question:
Mass of the plastic bag, m = 12.0 g = 
Magnitude of electric field, E = 
Angle made by the string, 
Now,
To calculate the net charge, Q on the ball:
Vertical component of the tension in the string, 
Horizontal component of the tension in the string, 
Now,
Balancing the forces in the x-direction:

(1)
Balancing the forces in the y-direction:

where
g = acceleration due to gravity = 
Thus


Use T = 0.1357 N in eqn (1):


Answer:
Explanation:
The equation for this is
f = μ
where f is the frictional force the block needs to overcome, μ is the coefficient of static friction, and
(that means that the normal force is the same as the weight of the block which has an equation of weight = mass times the pull of gravity). Filling in:
1.09 = μ(.413)(9.8) and
μ =
so
μ = .27
Answer:8.1 m
Explanation:
Given
ball is launched from height of 3 m
initial velocity 
considering the ball is thrown vertically upward
Using 
where,
u=initial velocity
v=final Velocity
a=acceleration
s=distance
At maximum height final velocity will be zero



Therefore maximum height w.r.t ground is 
Answer:
The time he can wait to pull the cord is 41.3 s
Explanation:
The equation for the height of the skydiver at a time "t" is as follows:
y = y0 + v0 · t + 1/2 · g · t²
Where:
y = height at time "t".
y0 = initial height.
v0 = initial velocity.
t = time.
g = acceleration due to gravity (-9.8 m/s² considering the upward direction as positive).
First, let´s calculate how much time will it take for the skydiver to hit the ground if he doesn´t activate the parachute.
When he reaches the ground, the height will be 0 (placing the origin of the frame of reference on the ground). Then:
y = y0 + v0 · t + 1/2 · g · t²
0 m = 15000 m + 0 m/s · t - 1/2 · 9.8 m/s² · t²
0 m = 15000 m - 4.9 m/s² · t²
-15000 m / -4.9 m/s² = t²
t = 55.3 s
Then, if it takes 4.0 s for the parachute to be fully deployed and the parachute has to be fully deployed 10.0 s before reaching the ground, the skydiver has to pull the cord 14.0 s before reaching the ground. Then, the time he can wait before pulling the cord is (55.3 s - 14.0 s) 41.3 s.
Answer:
90 m
Explanation:
We use an ecuation of uniformly accelerated motion, which allows us to find the distance traveled by the car from the moment that driver applies the brakes until it stops completely, that is, when its final speed is zero.

We isolate the variable d, knowing that the final speed
is zero
