Question

Rockets travel by pushing fuel backwards at high velocity. Which of the following does this demonstrate?

A) Conservation of energy

B) Conservation of velocity

C) Conservation of momentum

D) Newton's second law: F = ma

Answer #1

Rocket works on the
**conservation of momentum**. In a rocket, the fuel
burns and produces gas at high temperature. These gases are ejected
out of the rocket from a nozzle at the back side of the rocket with
high speed. Conservation of momentum dictates that if material
(gas) is ejected backward, the forward momentum of the remaining
rocket must increase since an isolated system (**rocket +
fuel**) cannot change its net momentum.

Therefore, the correct option is
**(C)** i.e.

**C) Conservation of
momentum**

A projectile of mass m = 5kg is thrown upward vertically with a
velocity v0 = 9 m/s
a) Starting with Newton's 2nd Law FNet = ma,
calculate the time to an accuracy of four decimal places at which
the maximum height is reached when no air resistance is
present.
b) Starting with Newton's 2nd Law FNet = ma,
calculate the time to an accuracy of four decimal places at which
the maximum height is reached when considering the following...

Q. Newton's second law is summarized in the equation F=ma. Which
of the following is true regarding this equation?
A. To use this equation, you need to add all the forces
together, accounting the different directions, before knowing what
to put for F.
B. It's impossible to get any information from this equation
until you know, ahead of time, exact values for F, m, and a.
C. To use this equation, you need to add all the forces together
numerically,...

Part A
Which of the following are different for a particle and its
antiparticle?
charge only
mass only
spin only
charge and mass
charge and spin
mass and spin
charge and mass and spin
Part B
Which conservation law is violated by particle-antiparticle
annihilation?
conservation of energy
conservation of momentum
conservation of charge
conservation of lepton number
none of these

Consider two railway trucks that can travel along a
straight railway track which defines the
x-axis. A laden truck of mass M = 6.6 × 103 kg and an
empty truck of unknown mass m
approach each other at constant velocity. The laden
truck has an initial velocity component
of ux = +2.0ms−1 which is half that of the initial
velocity component of the empty truck
(but in the opposite direction). After an elastic
collision, the velocity component of the...

1) Which of the following equations represents momentum
conservation?
a) ½ m1v12 + ½
m2v22 = ½
m1v1’2 + ½
m2v2’2. b)
m1v1 +m2v2 =
m1v1’ + m2v2’.
c) ¼ mv12 = ½ ( ½
mv12). d)
m1v1 + m2v2 = ½
m1v1’2 + ½
m2v2’2.
2)Which of the following equations represents energy
conservation?
a) ½ m1v12 + ½
m2v22 = ½
m1v1’2 + ½
m2v2’2. b)
m1v1 +m2v2 =
m1v1’ + m2v2’.
c) ¼
mv12 = ½ ( ½...

1.The momentum of an object is not dependent on which one of
the following quantities?
a) acceleration b) inertia
c) mass
d) velocity
2.Which one of the following statements concerning the
momentum of a system when the net force acting on the system has a
positive value is true?
a) The momentum of the system is increasing.
b) The momentum of the system is decreasing.
c) The momentum of the system is equal to zero kg m/s. d)
The...

1. An 80kg person dives off of a 20m high cliff with an upwards
velocity of 15 m/s into the water below. Neglect air
resistance.
a) How much potential energy does he have when he first jumps
off the cliff? *
b) How much kinetic energy does he have when he first jumps off
the cliff? *
c) We can neglect the potential energy the diver has when he is
just about the hit the water. Using the conservation of mechanical...

Of the following pairs of equal and opposite forces, which are
Newton's third-law interaction partners?
(1) The weight of a book resting on a table, and the normal
force pushing up on the book.
(2) the buoyant force on a metal cylinder hanging in a fluid,
and the contact force the cylinder exertsthe fluid.
(3) The weight of a ball falling at its terminal speed, and
the air resistance force on the ball.
A. 1only
B. land2
C. 2only
D....

1. Which of the following is true for angular motion?
a. A uniform net torque always causes an increase in angular
speed.
b. A uniform net torque always changes the direction of the angular
displacement vector.
c. A uniform net torque always change the magnitude of the
rotational inertia.
d. A uniform net torque will always cause a change of angular
momentum.
2. A net (non-zero) force acts on a particle. Which of the
following does not have to be...

Multiple Choice
An object in free fall undergoes an increase in:
Select one:
a. speed only
b. Acceleration only
c. Both speed and acceleration.
The impulse-momentum relationship is a result of Newton's:
Select one:
a. 1st Law of Motion
b. 2nd Law of Motion
c. 3rd Law of Motion
d. Law of Gravitation
Which of the following is a scalar?
Select one:
a. Velocity
b. Weight
c. Mass
d. Momentum
The language of science is:
Select one:
a. Mathematics
b....

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