Answer:
Work is done by friction = -165 J
Explanation:
Given:
Mass of block (m) = 15 kg
Ramp inclined = 28°
Friction force (f) = 30 N
Distance (d) = 5.5 m
Find:
Work is done by friction.
Computation:
Work is done by friction = -Fd
Work is done by friction = -(30)(5.5)
Work is done by friction = -165 J
Answer:
a) The distance of the object from the center of the Earth is 8.92x10⁶ m.
b) The initial acceleration of the object is 5 m/s².
Explanation:
a) The distance can be found using the equation of gravitational force:

Where:
G: is the gravitational constant = 6.67x10⁻¹¹ Nm²/kg²
M: is the Earth's mass = 5.97x10²⁴ kg
m: is the object's mass = 0.4 kg
F: is the force or the weight = 2.0 N
r: is the distance =?
The distance is:
Hence, the distance of the object from the center of the Earth is 8.92x10⁶ m.
b) The initial acceleration of the object can be calculated knowing the weight:
Where:
W: is the weight = 2 N
a: is the initial acceleration =?

Therefore, the initial acceleration of the object is 5 m/s².
I hope it helps you!
Answer:
The shortest distance in which you can stop the automobile by locking the brakes is 53.64 m
Explanation:
Given;
coefficient of kinetic friction, μ = 0.84
speed of the automobile, u = 29.0 m/s
To determine the the shortest distance in which you can stop an automobile by locking the brakes, we apply the following equation;
v² = u² + 2ax
where;
v is the final velocity
u is the initial velocity
a is the acceleration
x is the shortest distance
First we determine a;
From Newton's second law of motion
∑F = ma
F is the kinetic friction that opposes the motion of the car
-Fk = ma
but, -Fk = -μN
-μN = ma
-μmg = ma
-μg = a
- 0.8 x 9.8 = a
-7.84 m/s² = a
Now, substitute in the value of a in the equation above
v² = u² + 2ax
when the automobile stops, the final velocity, v = 0
0 = 29² + 2(-7.84)x
0 = 841 - 15.68x
15.68x = 841
x = 841 / 15.68
x = 53.64 m
Thus, the shortest distance in which you can stop the automobile by locking the brakes is 53.64 m
Answer:
Speed, Vfx = 7.619 m/s
Explanation:
Vertical distance, Dx = 5.4m
Horizontal distance, Dy = 8m
Acceleration due to gravity, g = 9.8m/s²
Initial speed, Vix = 0m/s²
To find the speed, we would use the second equation of motion to find the time, t;
Dx = Vixt + ½gt²
Substituting into the equation, we have;
5.4 = 0(t) + ½(9.8)*t²
5.4 = 0 + 4.9t²
Rearranging the equation, we have;
4.9t² = 5.4
t² = 5.4/4.9
t² = 1.1020
Taking the square root of both sides;
t = 1.050 secs.
For the speed;
Dy = Vfxt
Vfx = Dy/t
Vfx = 8/1.050
Vfx = 7.619 m/s
<em>Therefore, the speed of the pelican is 7.619 m/s</em>
The speed of sound is 340.29 meters per second.
Knowing that, we can calculate how high this cliff is by 340.29 * .4
The cliff is 340.29 * .4 = 136.12 meters