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2 years ago

Describe difference between instantaneous velocity and average velocity

Physics

1 answer:

Alexxandr [17]2 years ago

3 0

Answer:

The instantaneous velocity is the specific rate of change of position (or displacement) with respect to time at a single point (x,t) , while average velocity is the average rate of change of position (or displacement) with respect to time over an interval.Average velocity : Average velocity of a body is defined as the change in position or displacement (Δx) divided by time interval (Δt) in which that displacement occurs.

Instantaneous velocity : The instantaneous velocity of a body is the velocity of the body at any instant of time or at any point of its path .

velocity can be positive , negative or zero.

By studying speed and velocity we come to the result that at any time interval average speed of an object is equal or more than the average but instantaneous speed is equal to instantaneous velocity.

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A tennis ball connected to a string is spun around in a vertical, circular path at a uniform speed. The ball has a mass m = 0.15

Oksanka [162]

1) 5.5 N

When the ball is at the bottom of the circle, the equation of the forces is the following:

$T-mg = m\frac{v^2}{R}$

where

T is the tension in the string, which points upward

mg is the weight of the string, which points downward, with

m = 0.158 kg being the mass of the ball

g = 9.8 m/s^2 being the acceleration due to gravity

$m \frac{v^2}{R}$ is the centripetal force, which points upward, with

v = 5.22 m/s being the speed of the ball

R = 1.1 m being the radius of the circular trajectory

Substituting numbers and re-arranging the formula, we find T:

$T=mg+m\frac{v^2}{R}=(0.158 kg)(9.8 m/s^2)+(0.158 kg)\frac{(5.22 m/s)^2}{1.1 m}=5.5 N$

2) 3.9 N

When the ball is at the side of the circle, the only force acting along the centripetal direction is the tension in the string, therefore the equation of the forces becomes:

$T=m\frac{v^2}{R}$

And by substituting the numerical values, we find

$T=(0.158 kg)\frac{(5.22 m/s)^2}{1.1 m}=3.9 N$

3) 2.3 N

When the ball is at the top of the circle, both the tension and the weight of the ball point downward, in the same direction of the centripetal force. Therefore, the equation of the force is

$T+mg=m\frac{v^2}{R}$

And substituting the numerical values and re-arranging it, we find

$T=m\frac{v^2}{R}-mg=(0.158 kg)\frac{5.22 m/s)^2}{1.1 m}-(0.158 kg)(9.8 m/s^2)=2.3 N$

4) 3.3 m/s

The minimum velocity for the ball to keep the circular motion occurs when the centripetal force is equal to the weight of the ball, and the tension in the string is zero; therefore:

$T=0\\mg = m\frac{v^2}{R}$

and re-arranging the equation, we find

$v=\sqrt{gR}=\sqrt{(9.8 m/s^2)(1.1 m)}=3.3 m/s$

7 0

2 years ago

What is the current in a 120V circuit if the resistance is 20Ω?

Kaylis [27]

We have: $I=\frac{U}{R}=\frac{120}{20}=6A$

ok done. Thank to me :>

6 0

2 years ago

14. A rocket is shot up into the air and then comes back down and hits the ground 9.2 second later.

sineoko [7]

Answer:

105.8 m

46 m/s

Explanation:

From the time the rocket is launched to the time it reaches its maximum height:

v = 0 m/s

a = -10 m/s²

t = 9.2 s / 2 = 4.6 s

Find: Δy and v₀

Δy = vt − ½ at²

Δy = (0 m/s) (4.6 s) − ½ (-10 m/s²) (4.6 s)²

Δy = 105.8 m

v = at + v₀

0 m/s = (-10 m/s²) (4.6 s) + v₀

v₀ = 46 m/s

3 0

3 years ago

A bag of marbles is hanging motionless on a spring scale. What prevents the bag from falling?

Tanya [424]

Answer:

The vector sum of all forces acting on it is zero, its at equilibrium.

Explanation:

The bag of marbles hanging on a spring scale applies its weight downwards, which was counterbalanced by the reaction from the spring scale (obeying the Newton's third law of motion). And since no external forces are applied to the system, thus the equilibrium of the system.

If the weight of the bag is greater than the reaction from the spring scale, the scale breaks and the system would not be balanced.

7 0

3 years ago

Describe how impacts between objects in the solar system have helped create notable features in the solar system such as craters

konstantin123 [22]

When 'The big bang' happened lots of large pieces of molten rock was flying around the solar system. As the rocks crashed together they got bigger and as the got bigger they attracted more rocks. Some scientists think that a large piece of molten rock hit the still developing Earth and created the Moon. This impact also caused the Earths angled spin. The Moon got trapped in Earth's orbit and has stayed ever since. Small astroids have hit the Moon causing craters. The Earth doesn't get hit as much because of our thicker atmosphere. Hope this helps!

4 0

2 years ago