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2 years ago

7

Leanne is riding a bike. The forward force from her pedalling is 18N. There is a backward force of 6N from friction and a backwa

rd force of 12N from air resistance. Does the speed of the bike increase, decrease or not change?

2 answers:

Gelneren [198K]2 years ago

7 0

The speed of the bike does not change because the total force that is pushing her back is 18 Newtons and her forwards force is 18 newtons is her force is balanced and therefore will not change

olchik [2.2K]2 years ago

4 0

the net force acting on the bike is=
18 - 6 - 12 = 0 N.

Since the net force acting on the bike is zero, the bike is moving with constant velocity. Therefore, the speed of the bike does not change.

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If you wished to warm 100 kg of water by 15 degrees celsius for your bath, how much heat would be required? (give your answer in

Anit [1.1K]

For the answer to the question above,
<span>Q = amount of heat (kJ) </span>
<span>cp = specific heat capacity (kJ/kg.K) = 4.187 kJ/kgK </span>
<span>m = mass (kg) </span>
<span>dT = temperature difference between hot and cold side (K). Note: dt in °C = dt in Kelvin </span>

<span>Q = 100kg * (4.187 kJ/kgK) * 15 K </span>
<span>Q = 6,280.5 KJ = 6,280,500 J = 1,501,075.5 cal</span>

6 0

2 years ago

Ferdinand the frog is hopping from lily pad to lily pad in search of a good fly

loris [4]

Answer: $36.86\°$

Explanation:

According to the described situation we have the following data:

Horizontal distance between lily pads: $d=2.4 m$

Ferdinand's initial velocity: $V_{o}=5 m/s$

Time it takes a jump: $t=0.6 s$

We need to find the angle $\theta$ at which Ferdinand jumps.

In order to do this, we first have to find the <u>horizontal component (or x-component)</u> of this initial velocity. Since we are dealing with parabolic movement, where velocity has x-component and y-component, and in this case we will choose the x-component to find the angle:

$V_{x}=\frac{d}{t}$ (1)

$V_{x}=\frac{2.4 m}{0.6 s}$ (2)

$V_{x}=4 m/s$ (3)

On the other hand, the x-component of the velocity is expressed as:

$V_{x}=V_{o}cos\theta$ (4)

Substituting (3) in (4):

$4 m/s=5 m/s cos\theta$ (5)

Clearing $\theta$ :

$\theta=cos^{-1} (\frac{4 m/s}{5 m/s})$

$\theta=36.86\°$ This is the angle at which Ferdinand the frog jumps between lily pads

4 0

2 years ago

A shuttle on Earth has a mass of 4.5 E 5 kg. Compare its weight on Earth to its weight while in orbit at a height of 6.3 E 5 met

faltersainse [42]

Answer:

83%

Explanation:

On the surface, the weight is:

W = GMm / R²

where G is the gravitational constant, M is the mass of the Earth, m is the mass of the shuttle, and R is the radius of the Earth.

In orbit, the weight is:

w = GMm / (R+h)²

where h is the height of the shuttle above the surface of the Earth.

The ratio is:

w/W = R² / (R+h)²

w/W = (R / (R+h))²

Given that R = 6.4×10⁶ m and h = 6.3×10⁵ m:

w/W = (6.4×10⁶ / 7.03×10⁶)²

w/W = 0.83

The shuttle in orbit retains 83% of its weight on Earth.

4 0

2 years ago

In the winter sport of bobsledding, athletes push their sled along a horizontal ice surface and then hop on the sled as it start

Hitman42 [59]

Answer:

$v_f = 16.6 m/s$

Explanation:

As we know by force equation that force along the inclined planed due to gravity is given as

$F_g = mg sin\theta$

so the acceleration due to gravity along the plane is given as

$a = \frac{F_g}{m}$

now we have

$a = g sin\theta$

$a = (9.81 sin4.0)$

$a = 0.68 m/s^2$

now we know that

$v_f^2 - v_i^2 = 2 a d$

$v_f^2 - 9.2^2 = 2(0.68)(140)$

$v_f = 16.6 m/s$

4 0

2 years ago

A puppy weighing 3 kilograms races through the dog park. if she slows from a speed of 2 meters/second to 1 meter/second, what wi

Ne4ueva [31]

Your answer is A. If velocity decreases, your kinetic energy would also decrease.

6 0

2 years ago

Read 2 more answers