Answer:
b
Explanation:
because a elastic band uses elastic energy
Answer:
2. The metal surface exerts less frictional force because there are fewer bumps and irregularities on it than there are on the concrete.
Explanation:
Frictional force is a force that is exerted between two surfaces in contact with each other. Frictional force always opposes the direction of relative motion of the two surfaces: for instance, for a ball moving along a surface, the force of friction exerted by the surface on the ball points opposite to the direction of motion of the ball.
The magnitude of the frictional force for a ball moving on a flat surface is given by
where
is the coefficient of friction
m is the mass of the ball
g is the acceleration of gravity
The value of depends on the type of surface involved. In particular, a smooth surface has a smaller value of , while a rough surface will have a bigger value. In this case, we are comparing a smooth metal surface with concrete: since the metal surface has fewer bumps and irregularities than concrete, it has a smaller value of coefficient of friction, so it exerts less frictional force than concrete.
Answer:
Explanation:
Let lift force F be created by propellers at angle of Ф with the horizontal .
The vertical component of this force will balance the weight of helicopter and horizontal component will balance the air resistance .
F sinФ = mg = 2750 x 9.8 = 26950 N
F cosФ = 7510 N
Squaring and adding ,
F² = 26950² + 7510²
= 726302500 + 56400100
= 782702600
F = 27976.82 N .
Answer:
Mechanical weathering breaks rocks into smaller pieces without changing their composition. ... Chemical weathering breaks down rocks by forming new minerals that are stable at the Earth's surface. Water, carbon dioxide, and oxygen are important agents of chemical weathering.
Explanation:
