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3 years ago

A rock is thrown across a frozen pond with an initial speed of 8m/s. Which statement best describes the motion of the rock?

Physics

1 answer:

olga55 [171]3 years ago

7 0

Answer:

Option C: "The rock will slow down and eventually stop"

Explanation:

Since this is a real event, and not an ideal situation where there is no friction forces acting between the frozen pond and the rock, there is going to exist some force of dynamic friction (even small) acting between them. One can look up coefficients of dynamic friction between similar objects, and realize that some small force will be acting as the rock slides on the surface of the pond. That force acts always opposite the direction of movement, therefore decelerating the rock. The rock's speed will continue reducing in magnitude until it eventually stops.

Then, the selected answer is: "The rock will slow down and eventually stop."

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Man made objects that spread an impulse over a large amount of time

lyudmila [28]

Answer:

Examples of man-made objects that spread an impulse over a large amount of time are "airbags" in vehicles and "arrestor beds" (for trucks).

Explanation:

The question above is highly related to the topic about "Impulse" in Physics.

"Impulse" refers to an object's change in momentum (the amount of motion in an object) when a force acts upon it for an interval time. When it comes to providing safety to people when it comes to vehicular crashes, impulse plays a vital role.

Let's take the example of airbags in vehicles. Once a vehicle collides with another object, the driver is carried by a forward motion. Without airbags, the time is normally shorter for the driver to be stopped by the windshield. This results to a greater force. However, with the presence of air-bags, the driver will hit the airbag, instead of the windshield. This will lengthen the time of the impact, thus reducing the force.

Another example are the arrestor beds for trucks. Arrestor beds have been designed in order for trucks to stop, since it's hard to maneuver them. With the help of arrestor beds, trucks are able to come to a stop with a longer time interval, but decreased force.

5 0

2 years ago

The Burj Khalifa in Dubai is the world's tallest building. The structure is 828 m 828 m (2716.5 ft) and has more than 160 storie

Natasha_Volkova [10]

Answer:

h = height of the hotel room from the ground floor = 237.4m

Explanation:

Change in Potential Energy of tourist = ΔPE = PE2 – PE1 = mgh

PE1 is the potential energy of tourist at the ground floor

PE1 is the potential energy of tourist at the top (hotel room)

Given

PE1 = − 2.01 × 10⁵ J

PE2 = 0J

PE2 – PE1 = mgh

0 – (− 2.01 × 10⁵ J) = mgh

2.01 × 10⁵ J = 86.4×9.8×h

h = 2.01 × 10⁵/(86.4×9.8) = 237.4m

8 0

2 years ago

The speed of sound at temperature of________in the air is 360m/s.

Aleks04 [339]

Vo= 331+0.6T

360=331+0.6T

360-331=0.6T

29=0.6T

0.6T/29

T=6/290 so change it to simplest form and us formulas good luck

4 0

2 years ago

Read 2 more answers

A tennis ball is served horizontally from 2.4m above the ground at net is 12m away and point 0.9 high will be ball clear the net

Schach [20]

Explanation:

Let us first calculate long does it take to go 12m at 30m/s( assumed speed)

12/30 = 0.4 seconds

horizontal distance the ball drop in that time

H= (0)(0.4)+1/2(-9.8)(0.4)2

H= -0.78m

negative sign shows that the height of the ball at the net from the top.

Height of the ball at the net and from the ground= H1-H=2.4-0.78=1.62m

As 1.62m>0.9m so the ball will clear the net.

H_1= V0y t’ + ½ g t’^2

-2.4= (0)t’ + ½ (-9.8) t’^2

t’= 0.69s

X’=V0x t’

X’=(30)(0.96)

X’= 20.7m

3 0

2 years ago

What happens if you are riding your bike and hit something (like a curb) with the front wheel

evablogger [386]

You would flip forward or to the side

6 0

2 years ago