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bekas [8.4K]
3 years ago
5

An object, which is initially at rest, accelerates at a rate of 10 m/s2 . Its final position is 85 m from its initial position a

t the end of that acceleration. For how much time did it accelerate?
Physics
1 answer:
vesna_86 [32]3 years ago
4 0

Answer:

4.12 seconds

Explanation:

From the kinetic equation

s=ut+0.5at^{2} where s is the displacement, u is initial velocity, t is time of travel and a is acceleration.

Since the object is initially at rest, the initial velocity is zero hence the equation can be re-written as

s=0.5at^{2} and making t the subject of the formula

t=\sqrt {\frac {2s}{a}}

Substituting s for 85 m and a for 10 m/s2

t=\sqrt {\frac {2*85 m}{10}}=4.123105626 s

Therefore, time is approximately 4.12 seconds

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The maximum mass of a white dwarf is ______ times the mass of the sun.
Savatey [412]

Answer:

(A)

Explanation:

about 1.4 times the mass of our sun.

8 0
3 years ago
Two identical cylindrical vessels with their bases at the same level each contain a liquid of density 1.23 g/cm3. The area of ea
motikmotik

Explanation:

Work done by gravity is given by the formula,

           W = \rho A (h_{1} - h)g (h - h_{2}) ......... (1)

It is known that when levels are same then height of the liquid is as follows.

           h = \frac{h_{1} + h_{2}}{2} ......... (2)

Putting value of equation (2) in equation (1) the overall formula will be as follows.

       W = \frac{1}{4} \rho gA(h_{1} - h_{2})^{2})

           = \frac{1}{4} \times 1.23 g/cm^{3} \times 9.80 m/s^{2} \times 3.89 \times 10^{-4} m^{2}(1.76 m - 0.993 m)^{2})

           = 0.689 J

Thus, we can conclude that the work done by the gravitational force in equalizing the levels when the two vessels are connected is 0.689 J.

3 0
3 years ago
NEED HELP ASAP
Dafna11 [192]

Answers:

a) -2.54 m/s

b) -2351.25 J

Explanation:

This problem can be solved by the <u>Conservation of Momentum principle</u>, which establishes that the initial momentum p_{o} must be equal to the final momentum p_{f}:  

p_{o}=p_{f} (1)  

Where:  

p_{o}=m_{1} V_{o} + m_{2} U_{o} (2)  

p_{f}=(m_{1} + m_{2}) V_{f} (3)

m_{1}=110 kg is the mass of the first football player

V{o}=-7 m/s is the velocity of the first football player (to the south)

m_{2}=75 kg  is the mass of the second football player

U_{o}=4 m/s is the velocity of the second football player (to the north)

V_{f} is the final velocity of both football players

With this in mind, let's begin with the answers:

a) Velocity of the players just after the tackle

Substituting (2) and (3) in (1):

m_{1} V_{o} + m_{2} U_{o}=(m_{1} + m_{2}) V_{f} (4)  

Isolating V_{f}:

V_{f}=\frac{m_{1} V_{o} + m_{2} U_{o}}{m_{1} + m_{2}} (5)

V_{f}=\frac{(110 kg)(-7 m/s) + (75 kg) (4 m/s)}{110 kg + 75 kg} (6)

V_{f}=-2.54 m/s (7) The negative sign indicates the direction of the final velocity, to the south

b) Decrease in kinetic energy of the 110kg player

The change in Kinetic energy \Delta K is defined as:

\Delta K=\frac{1}{2} m_{1}V_{f}^{2} - \frac{1}{2} m_{1}V_{o}^{2} (8)

Simplifying:

\Delta K=\frac{1}{2} m_{1}(V_{f}^{2} - V_{o}^{2}) (9)

\Delta K=\frac{1}{2} 110 kg((-2.5 m/s)^{2} - (-7 m/s)^{2}) (10)

Finally:

\Delta K=-2351.25 J (10) Where the minus sign indicates the player's kinetic energy has decreased due to the perfectly inelastic collision

6 0
3 years ago
What s physics?
Alex777 [14]

The answer is (B. The study of Matter and Energy) but technically you could consider physics all of these as engineering is based on physics and that would be the study of inventions, chemistry and biology were both discovered because of physics, and physics invokes more math than any other subject as it applies math to the entire Universe.

7 0
3 years ago
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A ball bounces on the ground. How do the ball and the ground act on each other?(1 point)
liubo4ka [24]

Answer: A is your best answer.

Explanation:

It should be A because the when the ball bounces on the ground the ground will give it force to bounce again but also it wont go as high as it first did. Hope this helps:))

3 0
3 years ago
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