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Irina-Kira [14]
3 years ago
10

Suppose two children push horizontally, but in exactly opposite directions, on a third child in a wagon. The first child exerts

a force of 75.0N, the second child exerts a force of 90.0 N, friction is 12.0 N, and the most of the third child plus wagon is 23.0 kga)what is the system of interest if the acceleration of the child in the wagon is to be calculated
Physics
1 answer:
Naddika [18.5K]3 years ago
8 0

Answer:

Explanation:

75 N and 90 N are acting in opposite direction so net force = 90 - 75 = 15 N .

Friction force will act in the direction opposite to the direction of net force .

So friction force will act in the direction in which 75 N is acting .

Total force acting in the direction of 75 =  75 + 12 = 87 N

Net force acing on the third child = 90 - 87 = 3 N  

Its direction will be that in the direction of 90 N .

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4. Jimmy dropped a 10 kg bowling ball from a building that is 25 meters high.
KIM [24]

Answer:

The K.E of the bowling ball right before it hits the ground, K.E = 2450 J            

Explanation:

Given data,

The mass of the bowling ball, m = 10 kg

The height of the building, h = 25 m

The total mechanical energy of the body is given by,

                                     E = P.E + K.E

At height 'h' the P.E is maximum and the K.E is zero,

According to the law of conservation of energy, the K.E at the ground before hitting the ground is equal to the P.E at 'h'

Therefore, P.E at 'h'

                                  P.E = mgh

                                         = 10 x 9.8 x 25

                                         =  2450 J

Hence, the K.E of the bowling ball right before it hits the ground, K.E = 2450 J                                                                      

3 0
3 years ago
Find the current through a loop needed to create a maximum torque of 9.00 mN. The loop has 50 square turns that are 15.0 cm on a
Umnica [9.8K]

Answer:

10 A

Explanation:

τ = Maximum torque of the loop = 9 mN

N = Number of turns in the loop = 50

a = side of the loop = 15 cm = 0.15 m

A = Area of the loop = a² = 0.15² = 0.0225 m²

B = magnitude of magnetic field = 0.800 T

i = magnitude of current in the loop

Maximum torque of the loop is given as

τ = N B i A

Inserting the values

9 = (50) (0.8) (0.0225) i

i = 10 A

6 0
3 years ago
A red laser from a physics lab is marked as producing 632.8 nm light. When light from this laser falls on two closely spaced sli
goblinko [34]

Given Information:  

Wavelength of the red laser = λr = 632.8 nm

Distance between bright fringes due to red laser = yr = 5 mm

Distance between bright fringes due to laser pointer = yp = 5.14 mm

Required Information:  

Wavelength of the laser pointer = λp = ?

Answer:

Wavelength of the laser pointer = λp = ?

Explanation:

The wavelength of the monochromatic light can be found using young's double slits formula,

y = Dλ/d  

y/λ = D/d

Where

λ is the wavelength

y is the distance between bright fringes.

d is the double slit separation distance

D is the distance from the slits to the screen

For the red laser,

yr/λr = D/d

For the laser pointer,

yp/λp = D/d

Equating both equations yields,

yr/λr = yp/λp

Re-arrange for λp

λp = yp*λr/yr

λp =  (5*632.8)/5.14

λp = 615.56 nm

Therefore, the wavelength of the small laser pointer is 615.56 nm.

3 0
3 years ago
A solid cylinder is mounted above the ground with its axis of rotation oriented horizontally. A rope is wound around the cylinde
Romashka [77]

Answer:

(a)10.5 rad/s2

(b) 20.9 rev

(c) 47.27 m

Explanation:

As the block of mass 53 kg is falling and pulling on the rope. The tension force on the rope must be equal to the gravity acting on the block according to Newton's 3rd law

T = mg = 53*9.81 = 519.93  N

Since this tension force would rotate the cylinder freely without any friction. The torque created by this tension force is

To = TR = 519.93  * 0.36 = 187.17 Nm

This solid cylinder would have a moment of inertia around it's rotating axis of:

I = \frac{mR^2}{2} = \frac{275 * 0.36^2}{2} = 17.82kgm^2

(a)We can use Newton's 2nd law to calculate the angular acceleration exerted by such torque on the solid cylinder

\alpha = \frac{To}{I} = \frac{187.17}{17.82} = 10.5 rad/s^2

(b) With such constant angular acceleration, the angle it would make after 5s is

\theta = \frac{\alphat^2}{2} = \frac{10.5*5^2}{2} = 131.3 rad

Since each revolution equals to 2\pi rad of angle, we can calculate the number of revolution it makes

\frac{\theta}{2\pi} = \frac{131.3}{6.28} \approx 20.9 rev

(c) Assume the thickness of the rope is negligible (and its wounded radius is unchanging), we can calculate the rope length unwinded after rotating 131.3rad

\theta R = 131.3*0.36 = 47.27 m

3 0
3 years ago
A model rocket is launched with an initial upward velocity of.
REY [17]

Answer:
A model rocket is launched with an initial upward velocity of 215 ft/s.

Explanation:

3 0
2 years ago
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