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GaryK [48]
3 years ago
5

a person does 100 joules of work in pulling back the string of a bow. what will be the initial speed of a 0.5 kg arrow when it i

s fired from the bow?
Physics
1 answer:
eduard3 years ago
3 0

If all the energy she put into bending the bow is completely
transmitted to the arrow, then the arrow has the 100 joules
of kinetic energy when it leaves the bow.

                 Kinetic energy = (1/2) (mass) (speed)²

                         100 J        = (1/2) (0.5 kg) (speed²)

Divide each side by 0.25 kg:    100 J / 0.25 kg = speed²

 [ joule ] = [ newton-meter ] = kg-m²/sec²

                                                100 kg-m²/sec² / 0.25 kg = speed²

                                                 400 m²/sec² = speed²

Take the square root of each side:     speed = √400 m/s

                                                                                20 m/s

                                                                    (about 44.7 mph)                                           

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A 3.35 kg object initially moving in the positive x direction with a velocity of 4.90 m s collides with and sticks to a 1.88 kg
ahrayia [7]

Answer:

The final components of velocity of the composite object is 3.33 m/s.

Explanation:

Given;

mass of the first object, m₁ = 3.35 kg

initial velocity of the first object, u₁ = 4.90 m/s in positive x-direction

mass of the second object, m₂ = 1.88 kg

initial velocity of the second object, u₂ = 3.12 m/s in negative y-direction

initial momentum of the first object, P₁ = 3.35 x 4.9 = 16.415 kgm/s

initial momentum of the second object, P₂ = 1.88 x 3.12 = 5.8656 kgm/s

The resultant velocity of the two objects is given by;

R² = 16.415² + 5.8656²

R² = 303.858

R = √303.858

R = 17.432 kgm/s

Apply the principle of conservation of linear momentum for inelastic collision;

total initial momentum before = total final momentum after collision

P₁(x) + P₂(y) = Pf

R = Pf

R = v(m₁ + m₂)

17.432 = v(m₁ + m₂)

where;

v is the final components of velocity of the composite object

v = \frac{17.432}{m_1 + m_2} \\\\v = \frac{17.432}{3.35+1.88} \\\\v = 3.33 \ m/s

Therefore, the final components of velocity of the composite object is 3.33 m/s.

8 0
2 years ago
A wave is traveling from one medium to another.If the wave is partially transmitted an partially reflected from the boundary,wha
Kamila [148]

Answer: the answer is C

Explanation:

3 0
3 years ago
Someone plzzz helpppppp with this last question
vredina [299]

Answer:

I dont know someone deleted answers. But they were wrong. INERTIA IS CORRECT I DID THIS IN MY SCHOOL

C IS CORRECT

7 0
3 years ago
A driver with a 0.80-s reaction time applies the brakes, causing the car to have acceleration opposite the direction of motion.
jeka94

Answer:

a) During the reaction time, the car travels 21 m

b) After applying the brake, the car travels 48 m before coming to stop

Explanation:

The equation for the position of a straight movement with variable speed is as follows:

x = x0 + v0 t + 1/2 a t²

where

x: position at time t

v0: initial speed

a: acceleration

t: time

When the speed is constant (as before applying the brake), the equation would be:

x = x0 + v t

a)Before applying the brake, the car travels at constant speed. In 0.80 s the car will travel:

x = 0m + 26 m/s * 0.80 s = <u>21 m  </u>

b) After applying the brake, the car has an acceleration of -7.0 m/s². Using the equation for velocity, we can calculate how much time it takes the car to stop (v = 0):

v = v0 + a* t

0 = 26 m/s + (-7.0 m/s²) * t

-26 m/s / - 7.0 m/s² = t

t = 3.7 s

With this time, we can calculate how far the car traveled during the deacceleration.

x = x0 +v0 t + 1/2 a t²

x = 0m + 26 m/s * 3.7 s - 1/2 * 7.0m/s² * (3.7 s)² = <u>48 m</u>

4 0
3 years ago
A new ski area has opened that emphasizes the extreme nature of the skiing possible on its slopes. Suppose an ad intones "Free-f
Allushta [10]

Answer:

48.6°

Explanation:

The forward force, F equals the component of the weight along the slope.

So mgsinθ = ma where a = acceleration and θ = angle between the slope and the horizontal.

So a = gsinθ

Since we are given that a = 75%g = 0.75g,

0.75g = gsinθ

sinθ = 0.75

θ = sin⁻¹(0.75)

= 48.6°

5 0
3 years ago
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