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3 years ago

13

A girl is riding her bike at a speed of 12 m/s. She weighs 55 kg and her bike weighs 22 kg. What is the KE of the girl and her b

ike?

1 answer:

romanna [79]3 years ago

4 0

Answer:Kinetic energy of the girl and her bike is 5.544 kJ

Explanation:

Given that a girl is riding bike at speed of 12m/s

Also, mass of Girl is 55kg and mass of bike is 22kg

Let, Total mass of girl and bike be M=22+55=77kg

Now, Kinetic energy is given by K=

Hence, Kinetic energy of the girl and her bike will be

K=

K=

K=5544J

Thus, Kinetic energy of the girl and her bike is 5.544 kJ

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A wire must be replaced in a circuit by a new wire of the same material but nine times longer. If the new wire's resistance is t

Blizzard [7]

Answer:

three times the original diameter

Explanation:

From the wire's resistance formula, we can calculate the relation between the diameter of the wire and its length:

$R=\rho\frac{l}{\pi \frac{d^2}{4}}\\d=\sqrt{\rho \frac{4 l}{\pi R}}\\$

Here, d is the wire's diameter, $\rho$ is the electrical resistivity of the material and R is the resistance of the wire. We have $l'=9l$

$d'=\sqrt{\rho \frac{4 l'}{\pi R}}\\d'=\sqrt{\rho \frac{4 (9l)}{\pi R}}\\d'=3\sqrt{\rho \frac{4 l}{\pi R}}\\d'=3d$

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3 years ago

Specific heat is the amount of heat required to raise the temperature of a material by 1°C per what unit?

nydimaria [60]

The heat required to raise the temperature of the unit mass of a given substance by a given amount (usually one degree).

or C. Mass if you're on plato

3 0

3 years ago

Read 2 more answers

A boy throws a ball vertically up it returns the ground after 10 seconds find the maximum height reached by the ball

Akimi4 [234]

Answer:

Approximately $122.625\; {\rm m}$ (assuming that $g = 9.81\; {\rm m\cdot s^{-2}}$ , the ball was launched from ground level, and that the drag on the ball is negligible.)

Explanation:

Let $v_{0}$ denote the velocity at which the ball was thrown upward.

If the drag (air friction) on the ball is negligible, the ball would land with a velocity of exactly $(-v_{0})$ . The velocity of the ball would be changed from $v$ to $(-v_{0})\!$ (such that $\Delta v = (-v_{0}) - v_{0} = (-2\, v_{0})$ ) within $t = 10\; {\rm s}$ .

Also because the drag on the ball is negligible, the acceleration of the ball would be $a = -g = -9.81\; {\rm m\cdot s^{-2}}$ . Thus:

$\Delta v = a\, t = 10\; {\rm s} \times (-9.81\; {\rm m\cdot s^{-2}}) = -98.1\; {\rm m\cdot s^{-1}}$ .

Since $\Delta v = (-2\, v_{0})$ :

$-2\, v_{0} = \Delta v = -98.1\; {\rm m\cdot s^{-1}$ .

$\begin{aligned}v_{0} &= \frac{-98.1\; {\rm m\cdot s^{-1}}}{-2}= 49.05\; {\rm m \cdot s^{-1}}\end{aligned}$ .

The ball reaches maximum height when its velocity is $v_{1} = 0\; {\rm m\cdot s^{-1}}$ . Apply the SUVAT equation $x = ({v_{1}}^{2} - {v_{0}}^{2}) / (2\, a)$ to find the displacement $x$ between the original position (ground level, where $v_{0} = 49.05\; {\rm m\cdot s^{-1}}$ ) and the max-height position of the ball (where $v_{1} = 0\; {\rm m\cdot s^{-1}}$ .)

$\begin{aligned}x &= \frac{(0\; {\rm m\cdot s^{-1}})^{2} - (49.05\; {\rm m\cdot s^{-1}})^{2}}{2 \times (-9.81\; {\rm m\cdot s^{-2}})} \\ &\approx 122.625\; {\rm m\cdot s^{-1}}\end{aligned}$ .

7 0

2 years ago

Suppose that you lift four boxes individually, each at a constant velocity. The boxes have weights of 3.0 N, 4.0 N, 6.0 N, and 2

Alona [7]

Answer:

The vertical distance of weight 3.0 N = 4 m, vertical distance of weight 4.0 N = 3 m, vertical distance of weight 6.0 N = 2 m, vertical distance of weight 2.0 N = 6 m

Explanation:

Worked : work can be defined as the product of force and distance.

The S.I unit of work is Joules (J).

Mathematically it can be represented as,

W = F×d.................. Equation 1

d = W/F.............................. Equation 2

where W = work, F = force, d = distance.

<em>Given: W = 12 J</em>

(i) for the 3.0 N weight,

using equation 2

d = 12/3

d= 4 m.

(ii) for the 4.0 N weight,

d = 12/4

d = 3 m.

(iii) for the 6.0 N weight,

d = 12/6

d = 2 m.

(iv) for the 2.0 N weight,

d = 12/2

d = 6 m

Therefore vertical distance of weight 3.0 N = 4 m, vertical distance of weight 4.0 N = 3 m, vertical distance of weight 6.0 N = 2 m, vertical distance of weight 2.0 N = 6 m

8 0

3 years ago

Which of the following is not true about the Global Positioning Systems (GPS)?

Mrrafil [7]

Answer: Option (a) is the correct answer.

Explanation:

Global Positioning Systems (GPS) is a system which uses a network of satellites to construct maps. So, that it would be easy to trace location of a person, or to reach over a certain place.

It helps an individual by showing the route of destination wherever he/she wants to reach along with the total time to reach over the place.

Thus, GPS can determine the elevation of a given area and also it can determine latitude and longitude of a given area. As each GPS satellite broadcasts with a high power, narrow bandwidth, down link signal which can be received by our small hand held receiver antenna called mobile phone.

A GPS cannot determine the composition of soil on mountain ranges.

Thus, we can conclude that out of the given options, GPS can determine the composition of soil on mountain ranges is not true about the Global Positioning Systems (GPS).

7 0

3 years ago