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sergiy2304 [10]
3 years ago
5

You drive your car at a speed 40km/h for 1 hour, then slow down to 30km/h for the next 20km. How far did you drive, and what was

your average speed?
Physics
1 answer:
Bingel [31]3 years ago
8 0
Speed=distance/time, rearranging gives speed*time=distance therefore the first section of the journey yielded a total distance of 40km, the second journey was stated to be 20km which was completed in (20/30)*60=40minutes. Therefore the total journey was 60km which was completed in 1hr40 minutes so the average speed was (60/1.66..)=36km/h.
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If two identical cars are traveling at different velocities, which car has the greatest momentum ​
vodomira [7]

Answer:

The one with highest velocity

Explanation:

The momentum of an object is given by

p=mv

where

m is the mass of the car

v is the velocity of the car

In this problem, we have two identical cars: identical means they have same mass, so

m_1 = m_2 = m

The momentum of car 1 is

p_1 = mv_1

while the momentum of car 2 is

p_2 = mv_2

By comparing the two expressions, we see that the car with greatest momentum is the one with highest velocity, since the mass is the same.

8 0
3 years ago
Suppose a point charge is located at the center of a spherical surface. The electric field at the surface of the sphere and the
emmasim [6.3K]

Answer:

<em>The flux through the sphere will remain the same, and the magnitude of the electric field will increase by four times.</em>

Explanation:

The electric flux is the number of electric field, passing through a given area. It is proportional to the electric field strength and the area through which this field passes.

If the radius of the sphere is halved, the area of the sphere will reduce by square of the reduction, which will be four times. The electric field lines will become closer together, or technically increase by a fourth of its initial value. The resultant effect is that the electric flux will remain the same.

If originally,

Φ = EA cos∅

where Φ is the electric flux through the sphere

E is the electric field on the sphere

A is the area of the sphere.

If the area of the sphere is reduced to half, then,

the area reduces to A/4,

and the electric field increases to be 4E on the sphere.

The flux now becomes

Φ = 4E x A/4 cos∅

which reduces to

Φ = EA cos∅

which is the initial electric flux on the sphere.

8 0
2 years ago
A pencil rolls horizontally of a 1 meter high desk and lands .25 meters from the base of the desk. How fast was the pencil rolli
vovikov84 [41]

Answer: 0.55 m/s

Explanation:

This situation is related to projectile motion (also called parabolic motion), where the main equations are as follows:

x=V_{o} cos\theta t (1)

y=y_{o}+Vo sin \theta t + \frac{g}{2}t^{2} (2)

Where:

x=0.25 m is the horizontal displacement of the pencil

V_{o} is the pencil's initial velocity

\theta=0\° since we are told the pencil rolls <u>horizontally</u> before falling

t is the time since the pencil falls until it hits the ground

y_{o}=1 m  is the initial height of the pencil

y=0  is the final height of the pencil (when it finally hits the ground)

g=-9.8m/s^{2}  is the acceleration due gravity, always acting vertically downwards

Begining with (1):

x=V_{o} cos(0\°) t (3)

x=V_{o}t (4)

Finding t from (2):

0=1 m+ \frac{-9.8m/s^{2}}{2}t^{2} (5)

t=\sqrt{\frac{-2y_{o}}{g}} (6)

Substituting (6) in (4):

x=V_{o}\sqrt{\frac{-2y_{o}}{g}} (7)

Isolating V_{o}:

V_{o}=\frac{x}{\sqrt{\frac{-2y_{o}}{g}}} (8)

V_{o}=\frac{0.25 m}{\sqrt{\frac{-2(1 m)}{-9.8m/s^{2}}}} (9)

Finally:

V_{o}=0.55 m/s

4 0
3 years ago
What is the momentum of a child and a bicycle if the total mass of th
Sveta_85 [38]

bobo mag isip ayaw mag aral bobi

Explanation:

bobo ka boboboboboob

6 0
2 years ago
Give two ways of reversing the direction of the forces on the coil in the electric motor?​
nikklg [1K]

Answer:

Interchanging the poles of the magnet

Reversing the direction of the applied current

Explanation:

  1. The working of the electric motor is associated with Fleming's left-hand rule.
  2. It states that if a current-carrying conductor is placed inside a magnetic field, it experiences a force in the direction perpendicular to the direction of the electric current and magnetic field.
  3. These three physical quantities are placed in a mutually perpendicular direction.
  4. So, in order to reverse the direction of force, you have to either change the direction of the current or magnetic field.
4 0
3 years ago
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