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
beks73 [17]
3 years ago
5

A gang of robbers is escaping across city roofs at night. They come to the edge of one building and need to drop down to their g

etaway car, but aren't entirely sure if they can make the jump or need to head through the building. a) If one of them drops a pebble off the edge of the roof and it hits the ground two seconds later, how fast will they hit the ground if they jump? Give answers in terms of meters per second. b) How high up are they? Give answers in terms of meters. c) Is this a safe jump?
Physics
1 answer:
REY [17]3 years ago
3 0

Answer:

a) They will hit the ground with a speed of 19.6 m/s.

b) They are at a height of 20 m.

c) It is not a safe jump.

Explanation:

Hi there!

a) The equations of height and velocity in function of time of a free falling body are the following:

h = h0 + v0 · t + 1/2 · g · t²

v = v0 + g · t

Where:

h = height of the object at time t.

h0 = initial height.

v0 = initial velocity.

t = time.

g = acceleration due to gravity (-9.8 m/s² considering downward as negative direction).

v = velocity of the object at time t.

Using the equation of velocity, let's find the velocity at which they will hit the ground. The pebble is dropped (initial velocity = 0) and it takes 2 s to reach the ground:

v = v0 + g · t     (v0 = 0)

v = g · t

v = -9.8 m/s² · 2.0 s

v = -19.6 m/s

They will hit the ground with a speed of 19.6 m/s.

b)Now, we have to use the equation of height:

h = h0 + v0 · t + 1/2 · g · t²

If we place the origin of the frame of reference on the ground, we have to find the initial height (h0) knowing that at t = 2.0 s, h = 0 m

0 m = h0 - 1/2 · 9.8 m/s² · (2.0 s)²

h0 = 1/2 · 9.8 m/s² · (2.0 s)²

h0 = 20 m

They are at a height of 20 m.

c)According to a NASA paper (Issues on Human Acceleration Tolerance After Long-Duration Space Flights, figure 10), if you fall with a vertical velocity greater than 17 m/s it is unlikely that you will survive. So, it is not a safe jump.  

You might be interested in
You have to design a loop-the-loop for a new amusement park so that when each car passes the top of the loop inverted (upside-do
elena-14-01-66 [18.8K]

first of all go to slader .com to serach up this answer your welcome they have the best answers

6 0
3 years ago
An electric motor rotating a workshop grinding wheel at a rate of 151 rev/min is switched off. Assume constant angular decelerat
tamaranim1 [39]

Answer:

Explanation:

Initial angular velocity ω₀ = 151 x 2π / 60

= 15.8  rad /s

final velocity = 0

Angular deceleration α = 2.23 rad / s

ω² = ω₀² -  2 α θ

0 = 15.8² - 2 x 2.23 θ

= 55.99  rad

one revolution = 2π radian

55.99 radian = 55.99  / 2 π no of terns

= 9 approx .

8 0
3 years ago
A circuit with resistive elements of 220, 100, 57, and 43 produce what total resistance?
Korvikt [17]

The total resistance is 420 ohm.

A circuit with resistive elements of 220, 100, 57, and 43 produce what total resistance  

 R= 220+ 100+ 57+ 43

    = 420 Ω

What is resistance and its types?

Resistance is a measure of the opposition to current flow in an electrical circuit also known as ohmic resistance or electrical resistance. Ohms are measured as resistance, symbolized by the Greek letter omega (Ω). The ratio of the applied voltage to the current through the material is then known as resistance.

What causes resistance?

An electric current flows when electrons move through a conductor, such as a metal wire. The moving electrons can collide with the ions in the metal. This makes it more difficult for the current to flow, and causes resistance.

Learn more about resistance:

brainly.com/question/17563681

#SPJ4

8 0
1 year ago
How much current does a 10.0 Ω resistor draw from a 12 V battery?
Amiraneli [1.4K]
The answer would be B.
(V=IR, 12-10i, 12/10=1.2)
7 0
3 years ago
It is known that the kinetics of recrystallization for some alloy obeys the Avrami equation, andthat the value of n in the expon
trapecia [35]

Answer:8.76\times 10^{-3} min^{-1}

Explanation:

Given

n=5

0.3 fraction recrystallize after 100 min

According to Avrami equation

y=1-e^{-kt^n}

where y=fraction Transformed

k=constant

t=time

0.3=1-e^{-k(100)^5}

e^{-k(100)^5} =0.7

Taking log both sides

-k\cdot (10^{10}=\ln 0.7

k=3.566\times 10^{-11}

At this Point we want to compute t_{0.5}\ i.e.\ y=0.5

0.5=1-e^{-kt^n}

0.5=e^{-kt^n}

0.5=e^{-3.566\times 10^{-11}\cdot (t)^5}

taking log both sides

\ln 0.5=-3.566\times 10^{-11}\cdot (t)^5

t^5=1.943\times 10^{10}

t=114.2 min

Rate of Re crystallization at this temperature

t^{-1}=8.76\times 10^{-3} min^{-1}

3 0
3 years ago
Other questions:
  • To hoist himself into a tree, a 72.0-kg man ties one end of a nylon rope around his waist and throws the other end over a branch
    5·1 answer
  • What are the units for mass and volume
    8·1 answer
  • Look at the densities of the jovian planets given in figure 1. which of the following statements best describes the pattern of j
    6·2 answers
  • Technician A says that low compression on a single cylinder will cause an engine not to start. Technician B says that low compre
    14·1 answer
  • The sun warms equatorial regions of Earth ______ than the poles. This cause an area of ________ pressure to develop near the equ
    7·1 answer
  • What happens when two sound waves meet in destructive interference?
    14·1 answer
  • Test your prediction through calculation for the situations of the clay bob and the bouncy ball. Assume each has a mass of 100 g
    11·1 answer
  • The _____________ variable is observed, measured, and affected by the independent variable.​
    5·2 answers
  • 1.Narysuj obraz ołówka o długości 6 cm znajdującego się w odległości 8 cm od soczewki o ogniskowej 6 cm
    13·1 answer
  • A flowerpot falls from a window sill 36.5 m
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!