Static friction exists between a stationary object and the surface on which it is resting. It prevents an object from moving against the surface. Example: Static friction prevents an object like a book from falling of the desk, even if the desk is slightly tilted

Explanation:

hope this helped

7 0

3 years ago

A car traveling 20 m/s to the north collides with a car traveling 10 m/s to the

sergiy2304 [10]

Answer: C

Explanation:

In collision, whether elastic or inelastic collisions, momentum is always conserved. That is, the momentum before collision will be equal to the momentum after collision.

Change in momentum of the system will be momentum after collision minus total momentum before collision.

Since momentum is a vector quantity, the direction will also be considered.

Momentum = MV - mU

Let

M = 800 kg is going north

at V = 20 m/s and the other car

m= 800 kg is going south

at U = 10m/s.

Substitute all the parameters into the formula

Momentum = (800 × 20) - (800 × 10)

= 8000 kgm/s

The final momentum after collision will also be equal to 8000 kgm/s

Change in momentum = 8000 - 8000

Change in momentum = 0

5 0

3 years ago

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Would sound travel faster in a thick piece of metal (high density) or a large hollow piece of metal (low density)?

KiRa [710]

Answer:

See the explanation below

Explanation:

The speed of sound waves can be calculated using the following equation:

$v_{s}=\sqrt{\frac{E}{ro} } \\where:\\E = Young's modulus [GPa]\\ro = density of the material [kg/m^3]$

Let's do the exercise of comparing two materials one denser than the other, as is steel and aluminum

ro_steel = 7500 [kg/m^3]

ro_aluminum = 2700 [kg/m^3]

E_steel = 200 [GPa]

E_aluminum = 70 [GPa]

Now replacing the values in the equation for each material.

$v_{steel}=\sqrt{\frac{200*10^9}{7500}}\\ v_{steel}=5163[m/s]$

And for the aluminum

$v_{aluminum}=\sqrt{\frac{70*10^9}{2700} }\\ v_{aluminum}=5091.75[m/s]$

In this way we can see that sound propagates faster in denser materials.

6 0

3 years ago

The windshield of a speeding car hits a hovering insect. Consider the time interval from just before the car hits the insect to

HACTEHA [7]

Answer:

A. False

B True

C. False

D.False

E. True

F. False

G. False

H. False

I. True

Explanation:

A. False: The system being analyzed consists of the bug and the car. These are the two bodies involved in the collision.

B. True: The system being analyzed consists of the bug and the car

C. False: The magnitudes of the change in velocity are different from the car and the bug. The velocity of the bug changes from 0 to the velocity of the car, while there is no noticeable change in the velocity of the car

D.False: There is barely any change in the momentum of the car since the mass of the bug is very small.

E. True: Since the mass of the bug is small, and was initially at rest, the magnitude of the change in monentum will be large because the new velocity will be that of the car.

F. False: The system being analyzed consists of the bug and the car. Those are the two bodies involved in the collision

G. False: The car barely changes in velocity since the mass of the bug is small.

H. False: The car barely changes in momentum because the collision does not affect its speed so much. on the other hand the momentum change of the bug is large since its mass is small.

I. True: The bug which was initially at rest will begin moving with the velovity of the speeding car, while the car barely changes in its velocity

5 0

3 years ago