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2 years ago

10

If a force always acts perpendicular to an object's direction of motion, that force cannot change the object's kinetic energy.

1 answer:

laiz [17]2 years ago

5 0

This is very good conceptual question and can clear your doubts regarding work-energy theorem.
Whenever force is perpendicular to the direction of the motion, work done by that force is zero.
According to work-energy theorem,
Work done by all the force = change in kinetic energy.

here, work done = 0.
Therefore,
0=change in kinetic energy
This means kinetic energy remains constant.
Hope this helps

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A space shuttle orbits Earth at a speed of 21,000 km/hr. How far does it go in 3.5 hrs?

inn [45]

Since it travels at 21,000 kilometers per hour, you'd just multiply that with 3.5 to get 73,500. So your answer is 73,500.

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2 years ago

On James’s MP3 player, he has 12 sad songs and 40 upbeat songs that he wants to put into playlists. He wants to have the same nu

Anna [14]

Answer:

i would say a) two playlists

hope this helps!

Explanation:

4 0

2 years ago

Read 2 more answers

Q1: A runner is jogging in a straight line at a steady vr= 6.8 km/hr. When the runner is L= 2.4 km from the finish line, a bird

serious [3.7K]

Answer:

Q1: 3.2km

Q2: 4.8K

Explanation:

Q1:

So db is the distance of bird, and dr is the distance of runner

db = 2vr and the distance of bird is going to be 2 times greater than the runner.

formulas: db = 2vr & db = 2dr

db = 2dr
L + (L - x) = 2x
2L - x = 2x
2L = 3x
x = $\frac{2}{3}$ L

Insert it in x = $\frac{2}{3}$ L

$\frac{2}{3}$ (2.4km) = 1.6km

Now we use formula db = 2dr

db = 2L - x
db = 2(2.4km) - 1.6km
<u>db = 3.2km</u>

Q2:

Formulas: Vr = L /Δt & Vb = db/Δt

Vr = L/ Δt ⇒ Δt = $\frac{L}{Vr}$
$\frac{2.4km}{6.8km/hr}$
$\frac{6}{17}hr$

(Km cancel each other)

Vb = db/Δt ⇒ db = VbΔt
13.6km/hr $(\frac{6}{17}hr )$
<u>4.8km</u>

(hr cancel each other)

Hope it helps you :)

6 0

2 years ago

A horizontal water jet strikes a stationary vertical plate at a rate of 5 kg/s with a velocity of 35 km/hr. Assume that the wate

Nina [5.8K]

Answer:

48.6 N

Explanation:

rate of mass per second, dm/dt = 5 kg/s

Velocity, v = 35 km/hr = 9.72 m/s

Force acting on the plate

F = v x dm/dt

F = 9.72 x 5 = 48.6 N

Thus, the force acting on the plate is 48.6 N.

3 0

2 years ago

Which of the following describes a physical change? A. A marshmallow burns over an open flame. B. Icicles melt from a rooftop. C

AnnZ [28]

Answer:

B

Explanation:

Icicles melt from a rooftop

5 0

2 years ago