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g100num [7]
3 years ago
12

A sprinter accelerates from rest to 9.00 m/s in 1.38 s. what is her acceleration in (a) m/s2; (b) km/h2?

Physics
1 answer:
My name is Ann [436]3 years ago
4 0

a) 6.52 m/s^2

b) 23.47 km/hr^2


a) v = v0 + at --> 9 = 0 + a(1.38) --> a = 6.52

b) 6.52 m/s2  *  60 s2 / 1 min2  *  60 min2 / 1 hr2 = 23.47 km/hr2

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will the value of g be affected by the radius of the earth? consider the real shape of the earth. compare the acceleration due t
sp2606 [1]

Answer:

Yes, the value of g affected by the radius.

Explanation:

The formula for the force of gravity of 2 objects is

F_{gravity} = G\frac{m_{1}m_{2}}{r^2}, where m1 and m2 are the masses of the 2 objects, r is the radius, and G is the gravitational constant, which is approximately 6.67 \cdot 10^{-11}.

Therefore, as the radius if bigger, the force of gravity is going to be smaller exponentially.  

5 0
4 years ago
A river flows due south with a speed of 2.0 m/s .You steer a motorboat across the river; your velocity relative to the water is
mihalych1998 [28]

Answer:

a) v_m =\sqrt{v^2_x + v^2_y} = \sqrt{(2m/s)^2 +(4.8 m/s)^2}= 5.2 m/s

b) \theta= tan^{-1} \frac{v_y}{v_x} = tan^{-1} (\frac{2}{4.8})= 22.62 degrees and on this case to the South of the East.

c)t= \frac{w}{v_m}= \frac{600m}{4.8 m/s}= 125 s

d) Y = 2 m/s * 125 s = 250m

So it would be 250 to the South

Explanation:

Part a

For this case the figure attached shows the illustration for the problem.

We know that v_y = 2 m/s represent the velocity of the river to the south.

We have the velocity of the motorboard relative to the water and on this case is V_x= 4.8 m/s

And we want to find the velocity of the motord board relative to the Earth v_m

And we can find this velocity from the Pythagorean Theorem.

v_m =\sqrt{v^2_x + v^2_y} = \sqrt{(2m/s)^2 +(4.8 m/s)^2}= 5.2 m/s

Part b

We can find the direction with the following formula:

\theta= tan^{-1} \frac{v_y}{v_x} = tan^{-1} (\frac{2}{4.8})= 22.62 degrees and on this case to the South of the East.

Part c

For this case we can use the following definition

D = Vt

The distance would be D = w = 600 m and the velocity V = 4.8m/s and if we solve for t we got:

t= \frac{w}{v_m}= \frac{600m}{4.8 m/s}= 125 s

Part d

For this case we can use the same definition but now using the y compnent we have:

Y = v_y t

And replacing we got:

Y = 2 m/s * 125 s = 250m

So it would be 250 to the South

7 0
3 years ago
The driver of a train moving at 23m/s applies the breaks when it pases an amber signal. The next signal is 1km down the track an
pochemuha

Answer:

3.2 m/s

Explanation:

Given:

Δx = 1000 m

v₀ = 23 m/s

a = -0.26 m/s²

t = 76 s

Find: v

This problem is over-defined.  We only need 3 pieces of information, and we're given 4.  There are several equations we can use.  For example:

v = at + v₀

v = (-0.26 m/s²) (76 s) + (23 m/s)

v = 3.2 m/s

Or:

Δx = ½ (v + v₀) t

(1000 m) = ½ (v + 23 m/s) (76 s)

v = 3.3 m/s

Or:

v² = v₀² + 2aΔx

v² = (23 m/s)² + 2(-0.26 m/s²)(1000 m)

v = 3.0 m/s

Or:

Δx = vt − ½ at²

(1000 m) = v (76 s) − ½ (-0.26 m/s²) (76 s)²

v = 3.3 m/s

As you can see, you get slightly different answers depending on which variables you use.  Since 1000 m has 1 significant figure, compared to the other variables which have 2 significant figures, I recommend using the first equation.

8 0
4 years ago
If the net force acting on a stationary object is zero, then the object will A. remain at rest. B. accelerate in the direction o
ra1l [238]

The object will remain at rest

Newton's first law states that if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed unless it is acted upon by a force.

Here net force is zero

An object with a net force of zero acting on it will remain at rest, if initially at rest, or it will maintain a constant velocity.

F=MA

Force F=0

Than Acceleration A=0

With zero Acceleration stationary object  will remain at rest.

Hence Remain at rest is the correct answer

Learn more about Newton's law of motion here

brainly.com/question/25545050

#SPJ4

6 0
2 years ago
Based on Newton’s First Law, what would you expect to happen to a block that is pushed across ice and begins moving (You may ass
Montano1993 [528]
An unbalanced force.
Newton's first law states that an object in motion will stay in motion until a unbalanced force acts upon it.
3 0
3 years ago
Read 2 more answers
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