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sp2606 [1]
4 years ago
7

A pitcher tosses a baseball in the positive direction with a speed of 12 m/s. If the ball stops after 4 seconds, what is the ave

rage acceleration of the ball?
A.) -3 m/s/s
B.) +48 m/s/s
C.) +3 m/s/s
D.) -48 m/s/s
Physics
1 answer:
meriva4 years ago
8 0

Answer:

option c is correct

Explanation:

we know that time rate of change of velocity is called acceleration

so a=v/t

a=12/4

a=3m/s²

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Driving along a crowded freeway, you notice that it takes a time tt to go from one mile marker to the next. When you increase yo
ddd [48]

Answer:

38.6 mi/h

Explanation:

7.4 mi/h = 7.4mi/h * (1/60)hour/min * (1/60) min/s = 0.00206 mi/s

Let v (mi/s) be your original speed, then the time t it takes to go 1 mi/s is

t = 1/v

Since you increase v by 0.00206 mi/s, your time decreases by 15 s, this means

t - 15 = 1/(v+0.00206)

We can substitute t = 1/v to solve for v

\frac{1}{v} - 15 = \frac{1}{v + 0.00206}

We can multiply both sides of the equation with v(v+0.00206)

v+0.00206 - 15v(v+0.00206) = v

-15v^2 - 0.0308v + 0.00206 = 0

v= \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

v= \frac{0.03083\pm \sqrt{(-0.03083)^2 - 4*(-15)*(0.00205)}}{2*(-15)}

v= \frac{0.03083\pm0.35}{-30}

v = -0.01278 or v = 0.01 0724 mi/s

Since v can only be positive we will pick v = 0.010724 mi/s or 0.010724*3600 = 38.6 mi/h

6 0
4 years ago
Which of the following is a contact force?
3241004551 [841]

Answer:

b friction

Explanation:

Contact forces

Contact forces are forces that act between two objects that are physically touching each other. Examples of contact forces include:

Reaction force

An object at rest on a surface experiences reaction force. For example, a book on a table.

A box rests on a table. There are two arrows, equal in size but going in opposite directions, up and down, from the point where the box meets the table.

Tension

An object that is being stretched experiences a tension force. For example, a cable holding a ceiling lamp.

A box hangs from a rope. Two arrows which are equal in size act upwards and dowards from the top and bottom of the rope.

Friction

Two objects sliding past each other experience friction forces. For example, a box sliding down a slope.

A box rests on an incline. There are three arrows; one acting vertically downwards from the centre of the box’s base. One arrow acts perpendicular to the incline. One arrow acts up the incline.

Air resistance

An object moving through the air experiences air resistance. For example, a skydiver falling through the air.

A box falls from the sky. Two arrows, equal in size and opposite in direction act upwards from the box and downwards from the box

When a contact force acts between two objects, both objects experience the same size force, but in opposite directions. This is Newton's Third Law of Motion.

3 0
3 years ago
Help plz anyone ?????
Alexus [3.1K]

Answer:

Most likely, it will be harder to get strong magnets to change phase because they have more density.

3 0
3 years ago
3. At an early age, what happened to Cesar’s home?
Doss [256]

Answer: He died later in 78 BC and was accorded a state funeral. Hearing of Sulla's death, Caesar felt safe enough to return to Rome. Lacking means since his inheritance was confiscated, he acquired a modest house in the Subura, a lower-class neighbourhood of Rome. hope this helps. Can u give me brainliest

Explanation:

3 0
3 years ago
A ball is thrown vertically upwards at 19.6 m/s. For its complete trip (up and back down to the starting position), its average
stira [4]

When the ball reaches its original position, it will have the same speed (but would be traveling in the opposite direction). So the average speed is

\dfrac{19.6\,\frac{\mathrm m}{\mathrm s}-19.6\,\frac{\mathrm m}{\mathrm s}}{\Delta t}=0

regardless of how long the ball was in the air.

5 0
3 years ago
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