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Black_prince [1.1K]

2 years ago

12

A teacher pushed a 98 newton desk across a floor for a distance of 5 meters. He exerted a horizontal force of 20 N for four seco

nds. What was his power?

1 answer:

Pie2 years ago

7 0

Answer:

First let's find the work.

Work = Force*Displacement

= 20*5

= 100 Joules

Power = Work/Time

= 100/4

= 25 Watts

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A rubbit gets down from a rump which its /\x=0.85m in 0.5s, The rubbit's mass is 2kg, what is the net Force?

mestny [16]

Answer: 13.6 N

Explanation:

The equation of motion for the rabbit is:

$\Delta x=V_{ox}t+\frac{1}{2}a_{x}t^{2}$ (1)

Where:

$\Delta x=0.85 m$ is the distance traveled by the rabbit

$V_{ox}=0 m/s$ is the rabbit's initial velocity, assuming it started from rest

$t=0.5 s$ is the time

$a_{x}$ is the acceleration

Isolating $a_{x}$ :

$a_{x}=\frac{2 \Delta x}{t^{2}}$ (2)

$a_{x}=\frac{2 (0.85 m)}{(0.5)^{2}}$ (3)

$a_{x}=6.8 m/s^{2}$ (4)

On the other hand, the force $F_{x}$ is given by:

$F_{x}=m.a_{x}$ (5)

Where $m=2 kg$ is the mass of the rabbit

Substituting (4) in (5):

$F_{x}=(2 kg)(6.8 m/s^{2})$ (6)

Finally:

$F_{x}=13.6 N$

8 0

3 years ago

Find the acceleration of the system and the tension in the ropes for the system shown. The table mass is 30 kg and the hanging m

marusya05 [52]

The system's tension is 616 N and acceleration is 5.6 $m / s^{2}$

<u>Explanation:</u>

From newton’s second law of motion which state that net force acting on a body is product of mass of a body and acceleration of a body which is given as,

$F_{n e t}=m_{t o t} \times a$

Where,

$F_{n e t}$ is net force acting on body

$m_{\mathrm{tot}}$ is mass of body

a is acceleration of body

Given values

Table mass (m) = 30 kg

Hanging mass (m) = 40 kg

$a=\frac{F_{n e t}}{m_{\mathrm{tot}}}=\frac{m \times g}{m_{\mathrm{tot}}}$

Put the value for m = hanging mass = 40 kg and $g=9.8 \mathrm{m} / \mathrm{s}^{2}$ , we get

$a=\frac{40 \times 9.8}{30+40}=\frac{392}{70}=5.6 \mathrm{m} / \mathrm{s}^{2}$

The tension in the ropes, $T=(m \times g)+(m \times a)$

Here, m as hanging mass

T = tension, N or $k g m / s^{2}$

m = mass, kg

g = gravitational force, $9.8 \mathrm{m} / \mathrm{s}^{2}$

a = acceleration, $m / s^{2}$

$T = (40 \times 9.8)+(40 \times 5.6) = 392+224 = 616 N$

3 0

3 years ago

A loaf of bread has a mass of 2000g and a volume of 500 cm3. what is the density of the bread

Yuki888 [10]

Answer:

4g/cm^3

Explanation:

density = mass / volume

= 2000 / 500

= 4g/cm^3

7 0

3 years ago

In a physics laboratory experiment, a coil with 200 turns enclosing an area of 13.1 cm2 is rotated during the time interval 3.10

sergij07 [2.7K]

Answer:

A) $\Phi=83.84\times 10^{-9}$

B) $\Phi=0 Wb$

C) $emf=5.4090\times 10^{-4}V$

Explanation:

Given that:

no. of turns i the coil, $n=200$

area of the coil, $a=13.1 \times 10^{-4}\,m^2$

time interval of rotation, $t=3.1\times 10^{-2}\,s$

intensity of magnetic field, $B=6.4\times 10^{-5}\,T$

(A)

Initially the coil area is perpendicular to the magnetic field.

So, magnetic flux is given as:

$\Phi=B.a\,cos \theta$ ..................................(1)

$\theta$ is the angle between the area vector and the magnetic field lines. Area vector is always perpendicular to the area given. In this case area vector is parallel to the magnetic field.

$\Phi=6.4\times 10^{-5}\times 13.1 \times 10^{-4}\, cos 0^{\circ}$

$\Phi=83.84\times 10^{-9} Wb$

(B)

In this case the plane area is parallel to the magnetic field i.e. the area vector is perpendicular to the magnetic field.

∴ $\theta=90^{\circ}$

From eq. (1)

$\Phi=6.4\times 10^{-5}\times 13.1 \times 10^{-4}\, cos 90^{\circ}$

$\Phi=0 Wb$

(C)

According to the Faraday's Law we have:

$emf=n\frac{B.a}{t}$

$emf=\frac{200\times 6.4\times 10^{-5}\times 13.1 \times 10^{-4}}{3.1\times 10^{-2}}$

$emf=5.4090\times 10^{-4}V$

7 0

3 years ago

If a car changes ita velocity from 32km/hr to 54km/hr in 8.0 seconds, what is its acceleration

Andrews [41]

Firstly, let's convert the velocities in km/hr to m/s
32*1000/3600=8.89m/s
54*1000/3600=15m/s
From the formula, acceleration=V-U/t
15-8.89/8=0.76m/s²
hope this helps.

7 0

2 years ago