Answer:

Explanation:
Let hockey puck is moving at constant speed v
so here we have

so time taken by the puck to strike the wall is given as

now time taken by sound to come back at the position of shooter is given as


so we know that total time is 1.9 s




now we have


first one is true, there's no net force acting on it thats greater than another or making it unbalanced, if there was the object would be in some kind of motion
All scientist use meters, that way scientist can share information across country without needing to convert the data.
3. is air resistance
4. The large rock
An elastic collision is one in which the system does not experience a net loss of kinetic energy as a result of the collision. In elastic collisions, momentum and kinetic energy are both conserved.
<h3>Explain about the Elastic Collision?</h3>
A collision between two bodies in physics is referred to as an elastic collision if their combined kinetic energy stays constant. There is no net conversion of kinetic energy into other forms, such as heat, noise, or potential energy, in an ideal, fully elastic collision
An example of an elastic collision is when two balls collide at a pool table. It is an elastic collision when you throw a ball on the ground and it bounces back into your hand because there is no net change in the kinetic energy.
If there is no kinetic energy lost in the impact, the collision is said to be perfectly elastic. A collision is considered to be inelastic if any of the kinetic energy is converted to another kind of energy during the collision.
To learn more about Elastic Collision refer to:
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Answer:
If the system consists of the block only, the work done by the gravity is negative.
If the system consists of the block and the earth the work done by the gravity is zero.
Explanation:
If the system consists of the block only, then the system experiences two external forces: one exerted by the hand that lifts the block vertically upward and other exerted by the earth (gravity), which is opposed to the movement of the system, so the work done by gravity is negative.
On the other hand, if the system consists of the block and the earth, then only exists a external force which is the exerted by the hand. So, the force exerted by gravity is zero.