Answer: 1687.5 N
Explanation:
From the second law of motion given by Newton, Force is the rate change of momentum.

Mass of the baseball, m = 0.15 kg
Initial velocity,
(negative because direction of initial velocity is opposite to the final velocity)
Final velocity, 
The duration of collision, 
Force, 
Hence, the value of force is 1687.5 N.
Answer:
Therefore it is save to carry a 62kg adult
Explanation:
From the question we are told that:
Mass 
Height of supporting Rock 
Length of Board
Mass of board 
Mass of adult
Generally the moment of balance about wedge part about is mathematically given by



where

therefore

if N=0 at fallen person

Therefore it is save to carry a 62kg adult
Answer:

Explanation:
The electric field produced by a single point charge is given by:

where
k is the Coulomb's constant
q is the charge
r is the distance from the charge
In this problem, we have
E = 1.0 N/C (magnitude of the electric field)
r = 1.0 m (distance from the charge)
Solving the equation for q, we find the charge:
