Newton's second law states that the resultant of the forces applied to an object is equal to the product between the object's mass and its acceleration:

where in our problem, m is the mass the (child+cart) and a is the acceleration of the system.
We are only concerned about what it happens on the horizontal axis, so there are two forces acting on the cart+child system: the force F of the man pushing it, and the frictional force

acting in the opposite direction. So Newton's second law can be rewritten as

or

since the frictional force is 15 N and we want to achieve an acceleration of

, we can substitute these values to find what is the force the man needs:
Answer:
As point B is located inside the copper block so net electric field at point B is j.
Explanation:
Consider the figure attached below. The net electric field at location B,that is inside the copper block is zero because when a conductor is charged or placed in an electric field of external charges, net charge lies on the surface of conductor and there is no electric field inside the conductor. As point B is located inside the copper block so net electric field at point B is zero as well direction of net electric field at point B is zero.
Answer:
A. W = 6875.0 J.
B. W = -14264.6 J.
Explanation:
A. The work done by the rider can be calculated by using the following equation:

Where:
: is the force done by the rider = 25 N
d: is the distance = 275 m
θ: is the angle between the applied force and the distance
Since the applied force is in the same direction of the motion, the angle is zero.

Hence, the rider does a work of 6875.0 J on the bike.
B. The work done by the force of gravity on the bike is the following:
The force of gravity is given by the weight of the bike.
And the angle between the force of gravity and the direction of motion is 180°.
The minus sign is because the force of gravity is in the opposite direction to the motion direction.
Therefore, the magnitude of the work done by the force of gravity on the bike is 14264.6 J.
I hope it helps you!
Answer: I have more time to think about the wonderful things in life that we don't always appreciate.
Explanation:
Answer:
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The elevators which are on the tail section are used to control the pitch of the plane. A pilot uses a control wheel to raise and lower the elevators, by moving it forward to back ward. Lowering the elevators makes the plane nose go down and allows the plane to go down.
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