PLS HELP ME!!!

What happens to the kinetic energy of a snowball as it rolls across the lawn and gains mass?

nexus9112 [7]

Well, there's a lot of friction going on there, so the snowball gradually
loses kinetic energy just from bouncing and plowing through the snow
on the ground.

But I don't think you're asking about that. I think you're ignoring that
for the moment, and asking how its kinetic energy changes as its
mass increases. We know that

Kinetic Energy = (1/2) (mass) (speed²)

and THAT seems to say that more mass means more kinetic energy.
So maybe the snowball's kinetic energy increases as it picks up
more mass.

Don't you believe it !

Remember: Energy always has to come from somewhere ... a motor,
a jet, a push, gravity ... something ! It doesn't just appear out of thin air.
If the snowball were rolling down hill, then it could get more kinetic energy
from gravity. But if it's rolling on level ground, then it can never have any
more kinetic energy than you gave it when you pushed it and let it go.

If snow or leaves stick to it and its mass increases, then its speed must
decrease, in order to keep the same kinetic energy.

8 0

3 years ago

A dockworker loading crates on a ship finds that a 20 kg crate, initially at rest on a horizontal surface, requires a 70 N horiz

frez [133]

The coefficient of static friction is 0.357 and the coefficient of kinetic friction is 0.265.

Explanation:

Coefficient of static friction is defined as the proportionality constant for the frictional force between the crate and floor for starting the motion of crate and normal force acting on the crate. As the normal force of the crate is equal to the influence of acceleration due to gravity acting on the mass of the crate, the frictional force for static friction coefficient will be the force applied to move the crate.

Thus, $Static friction force = Coefficient of static friction * Normal force\\\\$

Since, the static friction force is 70 N, the normal force is equal to $Mass * acceleration due to gravity = 20 * 9.8 = 196 N$

So normal force is 196 N and static force is 70 N, and the ratio of static friction force to the normal force will give the coefficient of static friction.

$Coefficient of static friction = \frac{Static friction force}{Normal force}\\ \\Coefficient of static friction = \frac{70}{196} = 0.357$

Similarly, the coefficient of kinetic friction can be determined from the ratio of kinetic friction force to normal force. Here the kinetic friction force will be equal to the force applied on the crate to keep it moving.

$Coefficient of kinetic friction = \frac{Kinetic friction force}{Normal force}\\ \\Coefficient of kinetic friction = \frac{52}{196} = 0.265$

Thus, the coefficient of static friction is 0.357 and the coefficient of kinetic friction is 0.265.

6 0

3 years ago

An ideal spring hangs from the ceiling. A 1.95 kg mass is hung from the spring, stretching the spring a distance d=0.0865 m from

uranmaximum [27]

Answer:

kinetic energy = 0.1168 J

Explanation:

From Hooke's law, we know that ;

F = kx

k = F/x

We are given ;

Mass; m = 1.95 kg

Spring stretch; d = x = 0.0865

So, Force = mg = 1.95 × 9.81

k = 1.95 × 9.81/0.0865 = 221.15 N/m

Now, initial energy is;

E1 = mgL + ½k(x - L)²

Also, final energy; E2 = ½kx² + ½mv²

From conservation of energy, E1 = E2

Thus;

mgL + ½k(x - L)² = ½kx² + ½mv²

Making the kinetic energy ½mv² the subject, we have;

½mv² = mgL + ½k(x - L)² - ½kx²

We are given L=0.0325 m

Plugging other relevant values, we have ;

½mv² = (1.95 × 9.81 × 0.0325) + (½ × 221.15(0.0865 - 0.0325)² - ½(221.15 × 0.0865²)

½mv² = 0.62170875 + 0.3224367 - 0.82734979375

½mv² = 0.1168 J

7 0

3 years ago

Which one has more thermal energy?

Digiron [165]

Answer:

a bathtub full of warm water

Explanation:

Even though the water in a filled bathtub may be at the same temperature as water in a teacup, the water in the bathtub has more thermal energy because it contains a greater number of water molecules.

8 0

3 years ago

Read 2 more answers

Morgan does 50 J of work with a lever

Vikentia [17]

Answer:

46 J

Explanation:

Simply calculate the 92% of 50 Joules as:

0.92 * 50 J = 46 J

8 0

3 years ago