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3 years ago

Help please am stuck

Physics

1 answer:

inn [45]3 years ago

3 0

B. It increases by a factor of 4.

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You serve a volleyball with a mass of 2.1 kg. The ball leaves your hand with a speed of 30 m/s. The ball has—— energy. Calculate

Slav-nsk [51]

Answer:

945 j

Explanation:

You have just given the ball kinetic energy, which is given by the following equation:

KE= 1⁄2 m v2 = 1⁄2 (2.1 kg)(30 m/s)2 = 945 Joules

3 0

3 years ago

A 20-lb force acts to the west while an 80-lb force acts 45° east of north. The magnitu 80 lb 70 lb 067 lb 100 lb

natulia [17]

Answer:

option C

Explanation:

given,

force act on west = 20 lb

force act at 45° east of north = 80 lb

magnitude of force = ?

∑ F y = 80 cos 45⁰

F y = 56.57 lb

magnitude of forces in x- direction

∑ F x = -20 + 80 sin 45⁰

= 36.57 lb

net force

F = $\sqrt{F_x^2+F_y^2}$

F = $\sqrt{56.57^2+36.57^2}$

F = 67.36 lb≅ 67 lb

hence, the correct answer is option C

4 0

3 years ago

What is the kinetic energy of a ball that has a mass of 3kg and Is<br> moving at 5m/s?

Arada [10]

Answer:

E kin = 1/2 • m • v^2

E kin: kinetic energy

m: mass

v: velocity

Explanation:

6 0

2 years ago

If a sound with frequency fs is produced by a source traveling along a line with speed vs. If an observer is traveling with spee

Alexus [3.1K]

Answer:

457.81 Hz

Explanation:

From the question, it is stated that it is a question under Doppler effect.

As a result, we use this form

fo = (c + vo) / (c - vs) × fs

fo = observed frequency by observer =?

c = speed of sound = 332 m/s

vo = velocity of observer relative to source = 45 m/s

vs = velocity of source relative to observer = - 46 m/s ( it is taking a negative sign because the velocity of the source is in opposite direction to the observer).

fs = frequency of sound wave by source = 459 Hz

By substituting the the values to the equation, we have

fo = (332 + 45) / (332 - (-46)) × 459

fo = (377/ 332 + 46) × 459

fo = (377/ 378) × 459

fo = 0.9974 × 459

fo = 457.81 Hz

7 0

3 years ago

Bullets from two revolvers are fired with the same velocity. The bullet from gun #1 is twice as heavy as the bullet from gun #2.

IrinaVladis [17]

Answer:

option C

Explanation:

Let mass of the bullet be m and velocity be v

mass of gun be M and bullet be V

now,

using conservation of momentum for gun 1

(M+m) V' = 2 mv + 3 MV

V' = 0

3 M V = - 2 mv

momentum of gun 1 =- 2 mv---------(1)

now for gun 2

(M+m) V' = mv + MV

V' = 0

M V = - mv

momentum of gun 1 = -mv-----------(2)

dividing equation (1) by (2)

$\dfrac{P_m1}{P_m2} = \dfrac{- 2mv}{-mv}$

$\dfrac{P_m1}{P_m2} = \dfrac{2}{1}$

the correct answer is option C

7 0

3 years ago