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kirill [66]
3 years ago
12

A rifle can shoot a 4.20-g bullet at a speed of 965 m/s.a)Find the KE of the bullet at this speed.b) What work is done on the bu

llet if it starts from rest?c) If thework is done over a distance of 0.75 m, what is the average force on the bullet?d) If the bullet comes to rest by pushing 1.5 cm into metal, what is the magnitude and direction of the average force the metal exerts?
Physics
1 answer:
olga55 [171]3 years ago
6 0

Answer:

a)  1955.6 J

b) 1955.6 J

c) 2607 N

d) 110373 J

Explanation:

a) Kinetic\ Energy = \frac{1}{2} mv^2 = \frac{1}{2} \times  \frac{4.2}{1000} \times  965^2 = 1955.6 J

b) Work done on bullet should be increase in KE = 1955.6 J

c) Work done = Force \times displacement = KE of bullet

              F = \frac{1955.6}{0.75} = 2607 N

d) Work done to stop = KE = F_{stop} \times d_{stop}

F_{stop} = \frac{1955.6}{\frac{1.5}{100}} = 110373 J

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(a) As you ride on a Ferris wheel, your apparent weight is different at the top and at the bottom. Explain. (b) Calculate your a
otez555 [7]

Answer:

a. The component of the net force which make up the apparent weight are added to each other at the bottom and subtracted (the centripetal force from the weight) at the top)

b. Apparent weight at the top is approximately 519.06 N

Apparent weight at the bottom is approximately 558.94 N

Explanation:

a. The apparent weight at the top is different from the apparent weight at the bottom of a moving Ferris wheel because of the opposite direction in which the centripetal force acts at the top and the bottom, which are upwards and downwards respectively, while the weight acts downwards constantly

b. The given parameters are

The radius of the Ferris wheel, r = 7.2 m

The period for one complete revolution, t = 28 seconds

The angle covered in one revolution, θ = 2·π radian

The mass of the person riding on the Ferris wheel, the passenger  = 55 kg

Therefore, we have;

The angular speed, ω = Δθ/Δt = 2·π/(28)

From which we have;

Centripetal force, F_c = m × ω² × r

Substituting the known values, we have F_c = 55 kg × (2·π/(28 s))² × 7.2 m ≈ 19.94 N

The centripetal force, F_c = 19.94 N always acting outward from the center

Weight = Mass × Acceleration due to gravity

The weight of the passenger = 55 kg × 9.8 m/s² = 539 N

The weight of the passenger = 539 N always acting downwards

At the top of the Ferris wheel the the centripetal force is acting upwards and the weight is acting downwards

Therefore;

The net force, which is the apparent weight of the passenger at the top F_{NET_{Top}} = 539 N - 19.94 N ≈ 519.06 N

Apparent weight at the top ≈ 519.06 N

At the bottom of the Ferris wheel the weight is acting downwards and the centripetal force is also acting downwards

Therefore;

The net force at the bottom, which is the apparent weight of the passenger at the bottom F_{NET_{bottom}} = 539 N + 19.94 N ≈ 558.94 N

Apparent weight at the bottom ≈ 558.94 N.

5 0
3 years ago
Marys airplane trip took 5.8 hours for one-half of that time, the airplane flew at a constant speed of 640 miles per hour and fo
Olenka [21]
Distance is speed x time.  Half of the trip is 5.8/2 = 2.9hrs.
640 x 2.9 = 1856mi
580 x 2.9 = 1682mi
1856mi+1682mi=3538mi.

You could also calculate her average speed.  This is easy since it was divided in two equal time slices.  Average Speed = (640+580)/2 = 610mi/hr
Now 610mi/hr x 5.8hrs = 3538mi
7 0
3 years ago
If a rock is dropped from the top of a tower at the front of it and takes 3.6 seconds to hit the ground. Calculate the final vel
expeople1 [14]

Answer:

35.28m/s; 63.50m

Explanation:

<u>Given the following data;</u>

Time, t = 3.6 secs

Since it's a free fall, acceleration due to gravity = 9.8m/s²

Initial velocity, u = 0

To find the final velocity, we would use the first equation of motion;

V = u + at

Substituting into the equation, we have;

V = 0 + 9.8 * 3.6

V = 35.28m/s

Therefore, the final velocity of the penny is 35.28m/s.

To find the height, we would use the second equation of motion;

S = ut + \frac {1}{2}at^{2}

Substituting the values into the equation;

S = 0(3.6) + \frac {1}{2}*9.8*(3.6)^{2}

S = 0 + 4.9*12.86

S = 0.5 *36

S = 63.50m

Therefore, the height of the tower is 63.50m.

6 0
3 years ago
A conveyor belt is used to move sand from one place to another in a factory. The conveyor is tilted at an angle of 18° above the
brilliants [131]

Answer:

x = 2.044 m

Explanation:

given data

initial vertical component of velocity = Vy = 2sin18

initial horizontal component of velocity = Vx = 2cos18

distance from the ground yo = 5m

ground distance y = 0

from equation of motion

y = yo+ V_y t +\frac{1}{2}gt^2

0 = 5 + 2sin18+ \frac{1}{2}*9.8t^2

solving for t

t = 1.075 sec

for horizontal motion

x = V_x t

x = 2cos18*1.075

x = 2.044 m

8 0
3 years ago
Solve this question with explanation <br> Best answer will be brainliest <br> 40 points given
Yuliya22 [10]

Answer:

12 km/h

Explanation:

Average Speed = Distance / Time (or rate)

Pick a point on the graph for Ian and plug in values.

For example, 20 minutes -> 4km

Hence, Average speed = 4km ÷ 20 minutes = 0.2 km/min

0.2 km/min × 60 = 12 km/h

7 0
3 years ago
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