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3 years ago

Which statement best describes the energy changes that occur while a child is riding on a sled down a steep, snow-covered hill?

Physics

2 answers:

Tema [17]3 years ago

6 0

<span>Kinetic energy increases and potential energy decreases.
</span>

marishachu [46]3 years ago

3 0

The answer ur looking for is B

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3. A sprinter leaves the starting blocks with an acceleration of 4.5 m/s2. What is the

UkoKoshka [18]

Hi there! :)

$\large\boxed{v_{f} = 18 m/s}$

Use the following kinematic equation to solve for the final velocity:

$v_{f} = v_{i} + at$

In this instance, the runner started from rest, so the initial velocity is 0 m/s. We can rewrite the equation as:

$v_{f} = at$

Plug in the given acceleration and time:

$v_{f} = 4.5 * 4 = 18 m/s$

5 0

3 years ago

___ acceleration occurs when an object speeds up

AleksandrR [38]

Explanation:

Acceleration is defined as the change in velocity over time.

When there is an increment or increase in the magnitude of velocity of a moving body then it is known as positive acceleration.

Whereas when there is a decrease in magnitude of velocity of a moving body then it is known as negative acceleration.

Thus, we can conclude that positive acceleration occurs when an object speeds up.

3 0

3 years ago

Read 2 more answers

A 5.0-kg box has an acceleration of 2.0 m/s2 when it is pulled by a horizontal force across a surface with μK = 0.50. Find the w

Maslowich

Answer:a) 34.5 N; b) 24.5 N; c) 10 N; d) 1J

Explanation: In order to solve this problem we have to used the second Newton law given by:

∑F= m*a

F-f=m*a where f is the friction force (uk*Normal), from this we have

F= m*a+f=5 Kg*2 m/s^2+0.5*5Kg*9.8 m/s^2= 34.5 N

then f=uk*N=0.5*5Kg*9.8 m/s^2= 24.5N

the net Force = (34.5-24.5)N= 10 N

Finally the work done by the net force is equal to kinetic energy change so

W=∫Force net*dr= 10 N* 0.1 m= 1J

7 0

3 years ago

Read 2 more answers

You place an ice cube of mass 7.50×10−3kg and temperature 0.00∘C on top of a copper cube of mass 0.540 kg. All of the ice melts,

lbvjy [14]

Answer:

The value is $T_c = 12 .1 ^oC$

Explanation:

From the question we are told that

The mass of the ice cube is $m_i = 7.50 *10^{-3} \ kg$

The temperature of the ice cube is $T_i = 0^o C$

The mass of the copper cube is $m_c = 0.540 \ kg$

The final temperature of both substance is $T_f = 0^oC$

Generally form the law of thermal energy conservation,

The heat lost by the copper cube = heat gained by the ice cube

Generally the heat lost by the copper cube is mathematically represented as

$Q = m_c * c_c * [T_c - T_f ]$

The specific heat of copper is $c_c = 385J/kg \cdot ^oC$

Generally the heat gained by the ice cube is mathematically represented as

$Q_1 = m_i * L$

Here L is the latent heat of fusion of the ice with value $L = 3.34 * 10^{5} J/kg$

$Q_1 = 7.50 *10^{-3} * 3.34 * 10^{5}$

=> $Q_1 = 2505 \ J$

$2505 = 0.540 * 385 * [T_c - 0 ]$

=> $T_c = 12 .1 ^oC$

4 0

3 years ago

Density of water is 1000kg/m3. Find out the amount of mass of 5m3 water

Licemer1 [7]

Answer:

5000 m³

Explanation:

density = mass / volume

mass = density × volume

mass = 1000 × 5

mass = 5000 ( kg )

4 0

3 years ago