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Andreas93 [3]
3 years ago
15

A 4.0-kilogram penguin sliding across a large, flat icy surface with a constant velocity of 2.0 m s–1. Assuming that the surface

is frictionless, what size force is required to keep the penguin travelling at this speed?
Physics
1 answer:
Fiesta28 [93]3 years ago
3 0

Answer:

F=0

Explanation:

Newton's second law states that the sum of the external forces is equal to the product of the mass and the acceleration of the body

         F = m a

in this case it tells us that the velocity is constant so the acceleration must be zero,

therefore the sum of the external forces is zero; as they indicate that the surface is frictionless, there is no force applied to the system to maintain a constant speed

            F = 0

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_____________________ are structures in cardiac muscle tissue that allow impulses to spread across the heart more rapidly.
Darya [45]

Gap junctions in the intercalated discs allow impulses to be spread across the heart more quickly. This is because gap junctions allow particles/signals to pass through, thus making cells with gap junctions more able to interact.

One more thing—you posted this in the physics section rather than biology.

8 0
3 years ago
A 0.73-m aluminum bar is held with its length parallel to the east-west direction and dropped from a bridge. Just before the bar
Tasya [4]

Answer:

A)  B = 5.4 10⁻⁵ T, B) the positive side of the bar is to the West

Explanation:

A) For this exercise we must use the expression of Faraday's law for a moving body

            fem = -  \frac{d \phi }{dt}

            fem = - \frac{d (B l y}{dt}= - B l v- d (B l y) / dt = - B lv

            B = - \frac{fem}{l \ v}

we calculate

             B = - 7.9 10⁻⁴ /(0.73 20)

             B = 5.4 10⁻⁵ T

B) to determine which side of the bar is positive, we must use the right hand rule

the thumb points in the direction of the rod movement to the south, the magnetic field points in the horizontal direction and the rod is in the east-west direction.

Therefore the force points in the direction perpendicular to the velocity and the magnetic field is in the east direction; therefore the positive side of the bar is to the West

4 0
3 years ago
You want to move a 4- kg bookcase to a different place in the living room. If u push with a force of 65 n and the bookcase accel
IrinaK [193]

Answer:

1.65

Explanation:

The equation of the forces along the horizontal direction is:

F-F_f = ma (1)

where

F = 65 N is the force applied with the push

F_f is the frictional force

m = 4 kg is the mass

a=0.12 m/s^2 is the acceleration

The force of friction can be written as F_f = \mu R (2), where

\mu is the coefficient of kinetic friction

R is the normal force exerted by the floor

The equation of forces along the vertical direction is

R-mg=0 (3)

since the bookcase is in equilibrium. Substituting (2) and (3) into (1), we find

F-\mu mg = ma

And solving for \mu,

\mu = \frac{F-ma}{mg}=\frac{65-(4)(0.12)}{4(9.8)}=1.65

7 0
3 years ago
Calculate the power to move a 9j box in 20 seconds​
dalvyx [7]

Answer:

please find attached pdf

Explanation:

Download pdf
3 0
3 years ago
A solar cooker, really a concave mirror pointed at the sun, focuses the sun's rays 16.0 cm in front of the mirror. what is the r
VARVARA [1.3K]
The focal point of a concave mirror is halfway along the radius, therefore the radius would be 2•16= 32 cm
5 0
3 years ago
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