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Paladinen [302]
3 years ago
14

. A child drops a ball from a window. The ball strikes the ground in 3.0 seconds. What is the. A child drops a ball from a windo

w. The ball strikes the ground in 3.0 seconds. What is the
velocity of the ball the instant before it hits the ground?
Physics
1 answer:
Vsevolod [243]3 years ago
3 0

Answer:

30m/s

Explanation:

  • Use formula for height calculation: Time = √2h/√g
  • From here calculate height which comes out to be: 45m(if g is taken 10)
  • Then use formula for velocity calculation: v = √2gh

  • The velocity comes out to be 30m/s

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A 250 kg flatcar 25 m long is moving with a speed of 3.0 m/s along horizontal frictionless rails. A 61 kg worker starts walking
Anna11 [10]

Answer:

x=31.09m

Explanation:

p1=p2

The momentum of flatcar and the momentum of the worker so

The velocity of the worker is:

m_{f}*v_{f}=m_{w}*v_{w}\\\\v_{f}=\frac{m_{f}*v_{f}}{m_{w}}\\v_{f}=\frac{61kg*3.0\frac{m}{s}}{250kg}\\v_{f}=0.732\frac{m}{s}

The total motion has a total velocity and is

Vt=v_{w}+v_{f}\\Vt=0.732\frac{m}{s}+3.0\frac{m}{s}\\Vt=3.732\frac{m}{s}

The time the worker take walking is

t=\frac{x}{v_{w}}\\t=\frac{25m}{3\frac{m}{s}}=8.33s

Now the total time and the total velocity determinate the motion of tha flatcar how far has moved

x=t*Vt\\x=8.33s*3.732\frac{m}{s} \\x=31.09m

5 0
3 years ago
Initially, a particle is moving at 5.25 m/s at an angle of 35.5° above the horizontal. Three seconds later, its velocity is 6.0
ivolga24 [154]

Answer:

 a =( -0.32 i ^ - 2,697 j ^)  m/s²

Explanation:

This problem is an exercise of movement in two dimensions, the best way to solve it is to decompose the terms and work each axis independently.

Break down the speeds in two moments

initial

  v₀ₓ = v₀ cos θ

  v₀ₓ = 5.25 cos 35.5

v₀ₓ = 4.27 m / s

   v_{oy} = v₀ sin θ

 v_{oy}= 5.25 sin35.5

v_{oy} = 3.05 m / s

Final

vₓ = 6.03 cos (-56.7)

vₓ = 3.31 m / s

v_{y} = v₀ sin θ

v_{y} = 6.03 sin (-56.7)

v_{y} = -5.04 m / s

Having the speeds and the time, we can use the definition of average acceleration that is the change of speed in the time order

    a = (v_{f} - v₀) /t

    aₓ = (3.31 -4.27)/3

    aₓ = -0.32 m/s²

    a_{y} = (-5.04-3.05)/3

   a_{y} =  -2.697 m/s²

6 0
4 years ago
Which of the following is true when an object of mass m moving on a horizontal frictionless surface hits and sticks to an object
zhannawk [14.2K]

Answer:

c)

Explanation:

A collision is said to be elastic when the total kinetic energy is the same after the collision. The speed of objects that are stuck together will always be less than the initial speed of the object that was in motion given that the other particle was at rest. It is because the kinetic energy of the system was due to the moving object. The objects have a greater overall mass when they are stuck. If the kinetic energy is the same and the mass increases, the velocity must decrease.

3 0
3 years ago
Guyz... Its my first question in this app... Pls do answer​
Basile [38]

Answer:

1.414

Explanation:

Snell's law states:

n₁ sin θ₁ = n₂ sin θ₂

where n is the index of refraction and θ is the angle of incidence (relative to the normal).

The index of refraction of air is approximately 1.  So:

1 sin 45° = n sin 30°

n = sin 45° / sin 30°

n = 1.414

Round as needed.

6 0
3 years ago
Draw a distance over time graph of a dog that is tied to a 4 foot rope and travels in 1 complete circle
Soloha48 [4]
I think this is the answer. I hope you can understand.

6 0
3 years ago
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