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3 years ago

A group of bike riders took a 4 hour trip. During the first 3 hours, they traveled a total of 50 km, but

Physics

1 answer:

zlopas [31]3 years ago

7 0

Answer:

15km/hr

Explanation:

The average speed for the entire trip is the sum of the total distance traveled divided by the total time of the trip.

Total time = 4hr

distance for the first 3hrs = 50km

distance for the last 1hr = 10km

Total distance = 50km + 10km = 60km

Now;

Average speed = $\frac{total distance }{time taken}$

Insert the parameters and solve;

Average speed = $\frac{60km}{4hr}$ = 15km/hr

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A 100g block is initially compressing a spring 5.0 cm. The spring launches the block 50cm horizontally along the ground with a f

Setler [38]

Answer:

7200 N/m

Explanation:

Metric unit conversion

100g = 0.1 kg

5 cm = 0.05 m

50 cm = 0.5 m

As the block is released from the spring and travelling to height h = 1.5m off the ground, the elastics energy is converted to work of friction force and the potential energy at 1.5 m off the ground

The work by friction force is the product of the force F = 15N itself and the distance s = 0.5 m

$W_f = F_fs = 15*0.5 = 7.5 J$

Let g = 10 m/s2. The change in potential energy can be calculated as the following:

$E_p = mgh = 0.1*10*1.5 = 1.5 J$

Therefore, as elastic energy is converted to potential energy and work of friction:

$E_e = W_f + E_p$

$kx^2/2 = 7.5 + 1.5 = 9 J$

$k = 9*2/x^2 = 18/0.05^2 = 7200 N/m$

6 0

3 years ago

Which statement is true?

Jet001 [13]

Answer:

A. Speed is a scalar quantity and velocity is a vector quantity.

Explanation:

A scalar quantity is one that consists of only a numerical value.

Speed is a scalar quantity because only the instantaneous value is indicated, for example the speedometer of a car that tells you your speed at the moment but not where you are going or in what direction are you going.

On the other hand, velocity is a vector quantity. Because it is composed of a magnitude and a direction, for example 10m/s to the south is a velocity, and 10m/s is a speed.

6 0

2 years ago

Joseph studied whether different materials can block certain electromagnetic waves by testing television reception in different

Sedbober [7]

Joseph's experiment could be improved by using the same antenna at each part of the house during each trial instead of using different antenna. By doing so, he can obtain accurate results how is the signal in different part of the house under the same conditions (despite the location). So, he will see the dependence of the signal on the location. If he uses different antenna, than this antenna can also have influence of the signal.

5 0

3 years ago

Spring compressed 10cm by 100N force and held in place with Pin. Pin is pulled and block is pushed Up the incline. Uk(coefficien

otez555 [7]

The compression of 10 cm by a 100 N force on the plane that has a

coefficient of friction of 0.39 give the following values.

The velocity of the block after the Spring extends 7 cm is approximately 1.73 m/s

The height at which the block stops rising is approximately 1.1415 m

The length of the incline is approximately 1.536 m

<h3>How can the velocity and height of the block be calculated?</h3>

Mass of the block, m = 3 kg

$Spring \ constant, K = \dfrac{100 \, N}{0.1 \, m} = \mathbf{ 1000\, N/m}$

Coefficient of kinetic friction, $\mu_k$ = 0.39

Therefore, we have;

Friction force = $\mathbf{\mu_k}$ ·m·g·cos(θ)

Which gives;

Friction force = 0.39 × 3 × 9.81 × cos(48°) ≈ 7.68

Work done by the motion of the block, W ≈ 7.68 × d

The work done = The kinetic energy of the block, which gives;

$\mathbf{\dfrac{1}{2} \times k \cdot x^2 }= 7.68 \cdot d$

The initial kinetic energy in the spring is found as follows;

K.E. = 0.5 × 1000 N/m × (0.1 m)² = 5 J

The initial velocity of the block is therefore;

5 = 0.5·m·v²

v₁ = √(2 × 5 ÷ 3) ≈ 1.83

Work done by the motion of the block, W ≈ 7.68 N × 0.07 m ≈ 0.5376 J

Chane in kinetic energy, ΔK.E. = Work done

ΔK.E. = 0.5 × 3 × (v₁² - v₂²)

Which gives;

ΔK.E. = 0.5 × 3 × (1.83² - v₂²) = 0.5376

Which gives;

The velocity of the block after the Spring extends 7 cm, v₂ ≈ 1.73 m/s

The height at which the block will stop moving, h, is given as follows;

$At \ the \ maximum \ height, \ h, \ we \ have ; \ \dfrac{1}{2} \times 1000 \times 0.1^2 = 7.68 \times x$

Which gives;

$Length \ of \ the \ incline \ at \ maximum \ height, \ x_{max} =\dfrac{ 7.68 }{ \dfrac{1}{2} \times 1000 \times 0.1^2 } \approx 1.536$

The distance up the inclined, the block rises, at maximum height is therefore;

$x_{max}$ ≈ 1.536 m

Therefore;

h = 1.536 × sin(48°) ≈ 1.1415

The height at which the block stops rising, h ≈ 1.1415 m

From the above solution for the height, the length of the incline is he

distance along the incline at maximum height which is therefore;

Length of the incline, $x_{max}$ = 1.536 m

Learn more about conservation of energy here:

brainly.com/question/7538238

5 0

2 years ago

Why is the top of a wave called a crest

Molodets [167]

Answer: A crest is the highest point the medium rises to and a trough is the lowest point the medium sinks to. It is also a point on the wave where the displacement of the medium is at a maximum.

4 0

3 years ago