A boy shooting a rubber band across the classroom -->
Elastic potential energy transformed into kinetic energy
<span>The initial energy is the energy stored in the muscles of the boy's arm, which is elastic potential energy. This is converted into motion of the rubber, therefore kinetic energy
A child going down a slide on a playground --> </span>Gravitational potential energy transformed into kinetic energy
On top of the slide, all the energy of the child is gravitational potential energy due to its height with respect to the ground (E=mgh). when it moves down the slide, this is converted into kinetic energy, because the child acquires a speed v (E=1/2 mv^2)
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Rubbing your hands together to warm them on a cold day --> </span>Kinetic energy being transformed into thermal energy <span>
When rubbing hands, we are moving them (kinetic energy), and this energy raises the temperature of the hand's surface (thermal energy)
Turning on a battery operated light --> </span>
Chemical potential energy transformed into radiant energy <span>
A battery works by mean of chemical reactions (chemical potential energy), producing light (so, emitting energy by radiation, i.e. radiant energy)
Using a dc electric motor --> </span> Electrical energy transformed into kinetic energy<span>
A dc electric motor works using currents (so, electrical energy), and the energy produced can be used for example to accelerate a car (kinetic energy)
Using a gas power heater to warm a room --> </span>Chemical potential energy transformed into thermal energy
<span>A gas power heater burns gases (so, chemical reaction, i.e. chemical potential energy) to raise the temperature of the room (thermal energy)
Using a hand crank generator to produce electric current --> Kinetic energy transformed into electrical energy
In a hand-crank generator, the handle is being rotated (kinetic energy) in order to produce an electric current (electrical energy)
Using the light in your room that is plugged into the wall --> </span>Electrical energy transformed into radiant energy
<span>The lamp works by using electrical current flowing into a resistor (electrical energy) and it produces light, so it emits energy by electromagnetic radiation (radiant energy)
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Answer:
Explanation:
velocity of projection = vo
angle of projection = θ
When the ball is at maximum height, its vertical component of velocity is zero, So it has only the horizontal component of velocity at highest point.
velocity at highest point = vo Cos θ
The acceleration acting on the ball is only the acceleration due to gravity which always acts vertically downward.
So, teh acceleration of the ball at the highest point is g.
Answer:
Option B
Explanation:
For a system of block on inclined ramp shown in the attached image. From the attached image, the Normal force N, weight mg and frictional force f act on the block. The sum of vertical forces should be zero just as sum of vertical forces should be zero when the system is in equilibrium condition.
Taking sum of forces along the inclined plane we deduce that
[tex]f=mgsin \theta
[tex]
Therefore, option B is the correct option.
<em>Answers:</em>
<em>1. The hot soup will loose the heat and the ice water will gain the heat</em>
- If two jars are insulated inside the insulated box, the heat may not be transferred to outside of the box.
- According to II law of thermodynamics, Heat always flow from high temperature body to low temperature body, with out aid of external energy.
<em>So, from two points, it is concluded that The hot soup will lose heat and the ice water will gain the heat until they reach the thermodynamic equilibrium.</em>
<em>2. The particles in gases are farther apart and move faster </em>
- Particles in the gases are loosely packed (greater distance between particles compared to solids and liquids) and particles collide less often.
<em>Therefore conduction is weak in gases compared to solids and liquids.</em>
<em>3. Heat and milk by conduction; popping popcorn by radiation.</em>
- The heat can transfer from pot to the milk by conduction because they are in contact at boundaries, similarly the pot and the stove are in contact <em>so the conduction transfers heat from pot to the milk. </em>
- In microwave oven there is no direct contact (<em>no conduction</em>) of heat and popcorn, also there is no molecular momentum transfer <em>(means of no convection).</em>
<em>So obviously the heat transfer by radiation occurs in a microwave oven.</em>