Respuesta :
Answer is: 1/4 its old kinetic energy .
V₁ = 10 m/s.
V₂ = 5 m/s.
m₁ = m₂ = m.
E₁ = 1/2 · m₁ · V₁², E₁ = 1/2 · m · (10 m/s)² = 50 · m.
E₂ = 1/2 · m₂ · V₂², E₂ = 1/2 · m · (5 m/s)² = 12,5 · m.
E₂/E₁ = 12,5m / 50m = 0,25.
V - speed of semi-truck.
m - mass of semi-truck.
E - kinetic energy of semi-truck.
V₁ = 10 m/s.
V₂ = 5 m/s.
m₁ = m₂ = m.
E₁ = 1/2 · m₁ · V₁², E₁ = 1/2 · m · (10 m/s)² = 50 · m.
E₂ = 1/2 · m₂ · V₂², E₂ = 1/2 · m · (5 m/s)² = 12,5 · m.
E₂/E₁ = 12,5m / 50m = 0,25.
V - speed of semi-truck.
m - mass of semi-truck.
E - kinetic energy of semi-truck.
Connexus Physics pre-ap semester A final exam, all correct answers. And y’all better be freaking grateful, because it took a long time to type all this out.
1)
In the steps of the scientific method…
A. Interpreting results
2)
The radius of the Earth is…
B. 6.37 x 10^3 km
3)
Which of the following equations best describes…
D. y = 1/2x
4)
In the graph, what is the correct description…
C. Negative position
5)
The motion of a ball on an inclined plane is
described…
C. vi
6)
Acceleration due to gravity is also called
C. free-fall acceleration
7)
Which of the following is a physical quantity…
A. vector
8)
In a coordinate system, a vector is…
A. Cos (theta)
9)
Which of the following is an example of
projectile motion?
B. a thrown baseball
10)
A newton is equivalent to which…
A. kg * m/s^2
11)
In the free-body diagram shown below, which of
the following…
C. 4050 N
12)
A net force of 6.8 N accelerates a 31 kg scooter…
A. 0.22 m/s^2
13)
A change in the gravitational force acting…
C. Weight
14)
A passenger on a bus moving east sees a man
standing on a curb…
C. move west at a speed that is equal to the bus’s speed.
15)
In which of the following scenarios is no net
work done?
B. A car travels at a constant speed on a flat road.
16)
What is the kinetic energy of a 0.135 kg baseball
thrown at 40.0 m/s?
C. 108 J
17)
Which of the following refers to the sum of
kinetic energy…
D. mechanical energy
18)
Which of the following are not units of power?
B. J
19)
Which of the following…can be used to…calculate…change
in…momentum?
D. (delta)p = F (delta) t
20)
Two skaters stand facing…
B. their momenta are equal but opposite.
21)
In an inelastic collision…
D. the momentum of one object will increase by the amount that the momentum of
the other object decreases.
22)
When an object is moving with uniform circular
motion…tangential speed
C. is constant
23)
Which units would be the most appropriate to use
to…
A. newtons
24)
How would the speed of Earth’s orbit around the
sun change…
A. The speed would not change
25)
A girl pushes a box that has a weight of 450 N
up an incline…force of 150 N along…
B. 3.0
26)
According to the law of conservation of
mechanical energy,
C. Total energy must remain the same
27)
The potential energy of a 60 kg man…balcony 43
meters…
A. 25000 J
28)
If two small beakers of water, one at 70C and
one at 80C…
C. The final temperature is between 70C and 80C
29)
Why does sandpaper get hot when it is rubbed
against rusty metal?
C. Friction between the sandpaper and metal…
30)
Which of the following describes a substance in
which the temperature and pressure…
D. substance undergoing a change of state
31)
An ideal gas system is maintained at a constant
volume of 4 L. If pressure is constant…
A. 0 J
32)
Which of the following is a thermodynamic
process in which a system…
C. a cyclic process
33)
When a drop of ink mixes with water…
A The system’s entropy increases, and the total entropy of the universe
increases.
34)
A mass-spring system can oscillate…
D. elastic potential
35)
If a semi-truck decrease its speed from 10 m/s
to 5 m/s...
D. ¼ its old kinetic energy
36)
A boy releases a small 1 kg toy truck from rest
down a 5 meter high hill…
B. 50 J
37)
A car accelerates uniformly from 10 m/s to 20
m/s in 4.2 seconds…
A. 2.4 m/s^2
38)
What must the minimum tension of a single
vertical wire be to support a 1.5 kg picture?
A. 15 N
39)
Why does it seem harder to start sliding a couch across a carpeted floor than…
C. The opposing force of friction is greater when an object starts from rest…
40)
An elevator weighing 2.00 c 10^5 N is supported
by a steel cable…
Fw = mass * gravitational acceleration
2*10^5 = mass * 9.8
mass of the elevator = 20.4*10^3 kg
Fnet = Tension – Fw
mass * acceleration = Tension – 2*10^5
20.4*10^3 * 3 = Tension – 2*10^5
61200 = Tension – 2*10^5
Tension = (61200) + (2*10^5)
Tension = 2.61 * 10^5 newton
41)
A bullet with a mass of 6.00 g is fired through
a 1.25 kg block of wood on a frictionless surface.
0.006(896) + 0 = 0.006(435) + 1.25(V)
5.376 + 0 = 2.61 + 1.25(V)
5.376 = 2.61 + 1.25(V)
2.766 = 1.25(V)
V = 2.21 m/s
42)
Find the final equilibrium temperature when 10.0
g of milk at 10.0C is added to 1.60 x 10^2 g of coffee with a temperature of
90.0C.
Heat lost = heat gained
X = equilibrium temperature
Heat lost = 160(90-x)
Heat gained = 10(x-10)
14400 – 160x = 10x -100
170x = 14500
X = 14500/170
X = 85.25 degrees
