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]
2 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]2 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
Julian is having trouble coping with stress and setting goals. What is he most likely struggling with?
klio [65]
I would say Emotional health. Just because it is more sensable
6 0
3 years ago
Read 2 more answers
The source of the centripetal force that arises when a runner rounds a curve on a track is _____.
mel-nik [20]

It's actually Friction.

I just did the test and got it right.


3 0
3 years ago
Read 2 more answers
Bryce, a mouse lover, keeps his four pet mice in a roomy cage, where they spend much of their spare time (when they are not slee
user100 [1]

Answer:

I₁ = (7.78 i ^ - 6.71 j ^) 10⁻³ J s ,  I₂ = (-12.5 i ^ -14.6 j ^) 10⁻³ J s ,  I₃ = (19.1i ^ + 18.6 j ^) 10⁻³ J s  and I₄ = (-9.14i ^ + 7.24 j ^) 10⁻³ J s

Explanation:

The impulse is equal to the variation of the moment, to apply this relationship to our case, we will assume that initially the mouse was at rest

    I = Δp = m v_{f} -m v₀

    I = m (v_{f}  -v₀)

Bold indicates vector quantities, let's calculate the momentum of each mouse in for the x and y axes

We recommend bringing all units to the SI system

Mouse 1.

It has a mass of 22.3 g = 22.3 10⁻³ kg, a final velocity of (v = 0.349 i ^ - 0.301 j ^) m / s with an initial velocity of zero

    Iₓ = m (v_{fx}  - v₀ₓ)

    Iₓ = 22.3 10⁻³ (0.349 -0)

    Iₓ = 7.78 10⁻³ J s

   I_{y} = m (v_{fy}  -v_{oy} )

   I_{y} = 22.3 10⁻³ (-0.301)

   I_{y} = -6.71 10⁻³ J s

   I₁ = (7.78 i ^ - 6.71 j ^) 10⁻³ J s

Mouse 2

Mass 17.9 g = 17.9 10⁻³ kg

Speed ​​(-0.699 i ^ - 0.815 j ^) m / s

    Iₓ = m (v_{fx}  - v₀ₓ)

    Iₓ = 17.9 10⁻³ (-0.699 -0)

    Iₓ = -12.5 10⁻³ J s

    I_{y} = 17.9 10⁻³ (-0.815 - 0)

    I_{y} = -14.6 10⁻³ J s

   I₂ = (-12.5 i ^ -14.6 j ^) 10⁻³ J s

Mouse 3

Mass 19.1 g = 19.1 10⁻³ kg

Speed ​​(0.745i ^ + 0.975 j ^) m / s

    Iₓ = 19.1 10⁻³ (0.745 -0)

    Iₓ = 14.2 10⁻³ J s

    I_{y} = 19.1 10⁻³(0.975 -0)

    I_{y} = 18.6 10⁻³ J s

    I₃ = (19.1i ^ + 18.6 j ^) 10⁻³ J s

Mouse 4

Mass 10.1 g = 10.1 10⁻³ kg

Speed ​​(-0.905i ^ + 0.717j ^) m / s

    Iₓ = 10.1 10⁻³ (-0.905 -0)

    Iₓ = -9.14 10⁻³ J s

    I_{y} = 10.1 10⁻³ (0.717 -0)

    I_{y} = 7.24 10⁻³ J s

   I₄ = (-9.14i ^ + 7.24 j ^) 10⁻³ J s

8 0
3 years ago
Erica is participating in a road race. The first part of the race is on a 5.2-mile-long straight road oriented at an angle of 25
Sveta_85 [38]

Answer:

8.6 miles

Explanation:

We need to calculate the components of the total displacement along the east-west and north-south directions first.

In the first part, Erica moves 5.2 miles at 25∘ north of east. So the components of this displacement along the two directions are:

East: d_{1x} = 5.2 cos 25^{\circ}=4.7 mi

North: d_{1y} = 5.2 sin 25^{\circ}=2.2 mi

In the second part, Erica moves 5.0 miles north. So, the components of this displacement are:

East: d_{2x}=0

North: d_{2y} = 5.0 mi

So the components of the total displacement are

East: d_x = d_{1x}+d_{2x}=4.7 + 0 = 4.7 mi

North: d_y = d_{1y}+d_{2y}= 2.2 + 5.0 = 7.2 mi

Therefore the magnitude of the displacement, which is the straight-line distance from the starting point to the end of the race, is

d=\sqrt{d_x^2 +d_y^2}=\sqrt{4.7^2+7.2^2}=8.6 mi

5 0
3 years ago
What happens to the structure of an atom when the atom is ionised?​
Phoenix [80]

Answer: Explanation:

If the number of electrons is equal to the number of protons then the atom is uncharged and is electrically neutral. However, atoms can gain or lose electrons: increasing or decreasing the negative charge. Ionisation is the addition or removal of an electron to create an ion. ..Gaining an electron creates a negative ion.

7 0
2 years ago
Other questions:
  • A spring is 20cm long is stretched to 25cm by a load of 50N. What will be its length when stretched by 100N. assuming that the e
    12·1 answer
  • A closed system of mass 10 kg undergoes a process during which there is energy transfer by work from the system of 0.147 kJ per
    15·1 answer
  • A 1500 kg car is approaching a hill that has a height of 12 m. As the car reaches the bottom of the hill it runs out of gas and
    8·1 answer
  • A 400-turn circular coil (radius = 1.0 cm) is oriented with its plane perpendicular to a uniform magnetic field which has a magn
    10·1 answer
  • A. A cook leaves a plastic spoon and a wooden spoon in a pot of hot water for the same length of time. The spoons have the same
    14·2 answers
  • What happens to an object when an unbalanced force acts on it?
    11·1 answer
  • Curious George is whirling a 2.0 kg bunch of bananas on a smooth floor in a circular path having a radius of 0.50 m. What force
    9·1 answer
  • Why is the rotation system used in volleyball? Physics was the closest thing to PE
    8·2 answers
  • which of the following statements is a reasonable conclusion about the Arctic ecosystem? a)The number of offspring produced is a
    7·1 answer
  • A Hunter points his gun at a squirrel on a branch of a tree away from him. Assume he lies on the ground and that the moment he f
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!