1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
BigorU [14]
3 years ago
12

If she can throw each rock with a speed of 7.5 m/s relative to the ground, causing the wagon to move, how many rocks must she th

row per minute to maintain a constant average speed against a 3.9-N force of friction
Physics
1 answer:
Stels [109]3 years ago
5 0

Complete question:

A child sits in a wagon with a pile of 0.64-kg rocks. If she can throw each rock with a speed of 7.5 m/s relative to the ground, causing the wagon to move, how many rocks must she throw per minute to maintain a constant average speed against a 3.9-N force of friction

Answer:

The number of rocks per minutes thrown is 49 rocks/min

Explanation:

Given;

mass of the rock, m = 0.64 kg

speed of the rock, v = 7.5 m/s

frictional force, f_k = 3.9 N

For an object to move at a constant speed, the applied force must be equal to the frictional force.

f_k = N(F_a)\\\\f_k = N(\frac{mv}{t})\\\\f_k = \frac{N}{t} (mv)\\\\\frac{N}{t} = \frac{f_k}{mv}

where;

F_a is the applied force

N/t is the number of rocks per minutes thrown

Substitute the given parameters;

\frac{N}{t} = \frac{f_k}{mv}\\\\ \frac{N}{t} = \frac{3.9}{0.64*7.5}\\\\ \frac{N}{t} = 0.8125 \ \frac{rocks}{second} * \frac{60 \ seconds}{1 \ min} = 48.75 \ \frac{rocks}{min}  \

Approximately 49 rocks/min

You might be interested in
a 5.0-ft woman wishes to see a full length image of herself. what is the minimum length mirror required?​
nadezda [96]

Answer:

2.5 ft

Explanation:

minimum size of the mirror should be one half the person's height.

For this woman of 5 feet height, she would therefore need a mirror of length 2.5 feet

5ft ÷ 2 ft (half) = 2.5ft OR half of 5t is 2.5ft

4 0
1 year ago
A ruler has a division of 1mm. You use the ruler to measure a piece of paper. You find that it is 7.4 cm wide and 8.3 cm long. W
Anastaziya [24]

Answer:

<h2><em>6,142mm²</em></h2>

Explanation:

Given the dimension of a paper measured by a ruler as 7.4 cm wide and 8.3 cm long, the area of the paper is expressed using the area for calculating the area of a rectangle as shown;

Area of the piece of paper = Length * Width

Given length = 7.4cm

Length = 74mm (Since 10mm = 1cm)

Width = 8.3cm

Width (in mm) = 83mm

We converted to mm since the ruler used to measure has a division of 1mm.

Substituting the given values into the formula, we will have:

Area of the piece of paper = 74mm * 83mm

Area of the piece of paper = 6,142mm²

<em>Hence, the area of the piece of paper is 6,142mm²</em>

3 0
3 years ago
A gas expands and does PV work on its surroundings equal to 319 J. At the same time, it absorbs 136 J of heat from the surroundi
LiRa [457]

Answer:

The change in energy of the gas during the process is -1.83\times 10^{2} joules.

Explanation:

We can represent this process by the First Law of Thermodynamics, in which gas does work on its surroundings and absorbs heat from there to describe its change in energy. In other words:

Q_{in} - W_{out} = \Delta E

Where:

Q_{in} - Heat absorbed by the gas, measured in joules.

W_{out} - Work done by the gas, measured in joules.

\Delta E - Change in energy, measured in joules.

If we know that Q_{in} = 1.36\times 10^{2}\,J and W_{out} = 3.19\times 10^{2}\,J, the change in energy of the gas is:

\Delta E = 1.36\times 10^{2}\,J-3.19\times 10^{2}\,J

\Delta E = -1.83\times 10^{2}\,J

The change in energy of the gas during the process is -1.83\times 10^{2} joules.

3 0
3 years ago
What is the potential difference when the current in a circuit is 5mA and resistance is 30 Ohms
Mashcka [7]

<h2>\bf{ \underline{Given:- }}</h2>

\sf• \: The \:  current \:  in \:  a \:  circuit \:  is  \: 5 \: amps.  \: and  \: resistance \:  is \:  30 \:  Ohms.

\\

<h2>\bf{ \underline{To \:  Find :- }}</h2>

\sf{• \:  The  \: Potential  \: Difference. }

\\

\huge\bf{ \underline{ Solution:- }}

\sf According  \: to  \: the  \: question,

\sf•  \: Current \:  (I) = 5  \: Amps.

\sf• \:  Resistance  \: (R) = 30 \:  Ω

\sf{Potential \:  difference  \: means  \: Voltage \: ( V).}

\sf{We \:  know \: that, }

\bf \red{ \bigstar{ \: V = IR }}

\rightarrow \sf V =5 \times 30

\rightarrow \sf V =150

\\

\sf \purple{Therefore, \:  the \:  potential  \: difference  \: is  \: 150  \: v \: .}

4 0
3 years ago
HELP ASAP PLEASE!!!!!!!
pshichka [43]

Answer:a

Explanation: the plates shifts cracking making earthquakes

8 0
3 years ago
Other questions:
  • A 4.0-μF capacitor that is initially uncharged is connected in series with a 4.0-kΩ resistor and an ideal 17.0-V battery. How mu
    5·1 answer
  • Discuss renewable and nonrenewable resources. Give at least two advantages and two disadvantages of each. (4 points)
    15·1 answer
  • It’s for a cross word and mechanical doesn’t fit ☹️
    11·1 answer
  • What is the relationship between height and gravitational potential energy of water behind a dam?
    13·1 answer
  • A bodybuilder loads a bar with 550 Newton’s (125 pounds) of weight and pushes the bar over her head 10 times. Each time she lift
    12·1 answer
  • You are attending a county fair with your friend from your physics class. While walking around the fairgrounds, you discover a n
    12·1 answer
  • What color is the moon
    7·2 answers
  • Where is the frequency of infrasound in relation to the range of a human's ability to hear?
    12·1 answer
  • Suppose the Moon rose at 6 p.m. yesterday. What are the approximate rising times and phase of the Moon today?
    14·1 answer
  • How much kinetic energy is required to break through?
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!