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Leto [7]
1 year ago
7

A firecracker is thrown downward from a height of 2.75m above the ground, with a speed of 3.15m/s. Ignore air resistance, determ

ine the height above the ground that the firecracker would be moving at 5.23m/s.
Physics
1 answer:
3241004551 [841]1 year ago
4 0

Here in this question as we can see there is no air friction so we can use the principle of energy conservation

PE_i + KE_i = PE_f + KE_f

mgh_1 + \frac{1}{2}mv_i^2 = mgh_2 + \frac{1}{2}mv_f^2

now here we know that

h_1 = 2.75 m

v_i = 0

v_f = 5.23 m/s

now plug in all values in above equation

mg*2.75 + 0 = mgh + \frac{1}{2}m(5.23)^2

divide whole equation by mass "m"

9.8*2.75 = 9.8*h + \frac{1}{2}*27.35

9.8*h = 13.27

h = 1.35 m

so height of the ball from ground will be 1.35 m

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A toy rocket engine is securely fastened to a large puck that can glide with negligible friction over a horizontal surface, take
adell [148]

Answer:

F_{x}=2.31N to the right.

F_{y}=2.1N to in the upwards direction.

Explanation:

In order to solve this problem, we must first start by drawing a diagram of the situation. (See attached diagram).

So, remember that a force is determined by multiplying the mass of the parcticle by its acceleration:

F=ma

so in order to find the components of the force, we need to start by finding its acceleration.

Acceleration is found by using the following formula:

a=\frac{V_{f}-V{0}}{t}

so we can subtract the two vectors, like this:

a=\frac{(6.00i+4.0j)m/s-1.60i m/s}{8s}

which yields:

a=\frac{(4.4i+4.0j)m/s}{8s}

or:

a=(0.55i + 0.5j) m/s^{2}

so now I can find the components of the force:

F=(4.2kg)(0.55i + 0.5j) m/s^{2}

which yields:

F=(2.31i+2.1j)N

so the components of the force are:

F_{x}=2.31N to the right.

F_{y}=2.1N to in the upwards direction.

6 0
1 year ago
You are on vacation in San Francisco and decide to take a cable car to see the city. A 5800-kgkg cable car goes 260 mm up a hill
Stella [2.4K]

Answer:

4.325\times10^6J

Explanation:

Mass of the cable car, m = 5800 kg

It goes 260 m up a hill, along a slope of \theta=17^o

Therefore vertical elevation of the car = 260sin\theta=260sin17^o=76.0166m

Now, when you get into the cable car, it's velocity is zero, that is, initial kinetic energy is zero (since K.E. = \frac{1}{2} mv^2). Similarly as the car reaches the top, it halts and hence final kinetic energy is zero.

Therefore the only possible change in the cable car system is the change in it's gravitational potential energy.

Hence, total change in energy = mgh = 5800\times9.81\times76.0166J=4.325\times10^6J

where, g = acceleration due to gravity

h = height/vertical elevation

4 0
2 years ago
Jim stands beside a wide river and wonders how wide it is. he spots a large rock on the bank directly across from him. he then w
LuckyWell [14K]

To solve this problem, we must imagine that Jim’s initial position, the position of the rock, and Jim’s final position all connects to form a triangle. Now we can imagine that the triangle is a right triangle with the 90° angle on the initial position.

The angle of 30° is directly opposite to the length of his total stride while the width of the river is the side adjacent to the angle. Therefore can use the tan function to solve for the width of the river:

tan θ = opposite side / adjacent side

tan 30 = total stride distance / width of river

where total stride distance = 65 * 0.8 = 52 m

width of river = 52 m / tan 30

<span>width of river = 90.07 m</span>

7 0
1 year ago
A pickup truck starts from rest and maintains a constant acceleration a0. After a time t0, the truck is moving with speed 25 m/s
Anastaziya [24]

Answer:

the correct answer is c     v₁> 12.5 m / s

Explanation:

This is a one-dimensional kinematics exercise, let's start by finding the link to get up to speed.

            v² = v₀² + 2 a₁ x

as part of rest v₀ = 0

           a₁ = v² / 2x

           a₁ = 25² / (2 120)

           a₁ = 2.6 m / s²

now we can find the velocity for the distance x₂ = 60 m

           v₁² = 0 + 2 a1 x₂

           v₁ = Ra (2 2,6 60)

           v₁ = 17.7 m / s

these the speed at 60 m

we see that the correct answer is c     v₁> 12.5 m / s

5 0
2 years ago
A copper wire has radius 0.800 mm and carries current I at 20.0°C. A silver wire with radius 0.500 mm carries the same current a
IgorC [24]

Answer:

Ecu/Eag = 0.46

Explanation:

E = PI/A

Ecu = Pcu × I/A

Pcu = 1.72×10^-8 ohm-meter

r = 0.8 mm = 0.8/1000 = 8×10^-4 m

A = πr^2 = π×(8×10^-4)^2 = 6.4×10^-7π

Ecu = 1.72×10^-8I/6.4×10^-7π = 0.026875I/1

Eag = Pag × I/A

Pag = 1.47×10^-8 ohm-meter

r = 0.5 mm = 0.5/1000 = 5×10^-4 m

A = πr^2 = π × (5×10^-4)^2 = 2.5×10^-7π

Eag = 1.47×10^-8I/2.5×10^-7π = 0.0588I/π

Ecu/Eag = 0.026875I/π × π/0.0588I = 0.46

7 0
2 years ago
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