Please answer. give full explanation.

Physics

1 answer:

Ad libitum [116K]3 years ago

4 0

Work done=F *s*cos theta
Work done in this case can only be in the direction in which the electrons move.Thus cos theta is multiply to find the component of the force ( acting on an object doing work) which acts in the direction of propagation on movement of the object.Anyway,as in this case ,as magnetic field act only perpendicularly (at 90°) to electric fields(those are the electrons)no work is done.This is cause at 90°,there is no component of the magnetic field exiting of force in the direction of propagation of the electric field (electrons),as cos of 90 ° is 0, no work is done by the magnetic field.(as the whole product becomes zero regardless of the force or the displacement/distance

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A frog jumps vertically upward from a 20m tall building with an initial velocity of 8.1m/s. How high above the ground will the f

topjm [15]

Answer:

Explanation:

Consider the initial position of the frog (20 m above ground) as the reference position. All measurements are positive measured upward.

Therefore,

u = 10 m/s, initial upward velocity.

H = - 20 m, position of the ground.

g = 9.8 m/s², acceleration due to gravity.

Part (a)

When the frog reaches a maximum height of h from the reference position, its velocity is zero. Therefore

u² - 2gh = 0

h = u²/(2g) = 10²/(2*9.8) = 5.102 m

At maximum height, the frog will be 20 + 5.102 = 25.102 m above ground.

Answer: 25.1 m above ground

Part (b)

Let v = the velocity when the frog hits the ground. Then

v² = u² - 2gH

v² = 10² - 2*9.8*(-20) = 492

v = 22.18 m/s

Answer: The frog hits the ground with a velocity of 22.2 m/s

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4 years ago

The specific heat of aluminum is 0.90 J/gC . How much heat is given off when 25 grams of aluminum is cooled from 55 C to 25 C?

xxMikexx [17]

Answer:

Q = 675 [J]

Explanation:

We can calculate the amount of heat transfer by means of the following expression that includes the mass and temperature change in a body as a function of the specific heat.

$Q=m*C_{p}*(T_{initial}-T_{final})$