Answer:
a= - 6.667 m/s²
Explanation:
Given that
The initial speed of the box ,u= 20 m/s
The final speed of the box ,v= 0 m/s
The distance cover by box ,s= 30 m
Lets take the acceleration of the box = a
We know that
v²= u ² + 2 a s
Now by putting the values in the above equation we get
0²=20² + 2 a x 30

a= - 6.667 m/s²
Negative sign indicates that velocity and acceleration are in opposite direction.
Therefore the acceleration of the box will be - 6.667 m/s² .
Answer:
Option B
Explanation:
<h3>According to Newton's third law, for every reaction there will be equal and opposite reaction</h3>
Here in this case the force of the club hitting the golf ball will be in one direction and the force acting on club due to golf ball will be in opposite direction and magnitude of this force will be same as the magnitude of the force of the club hitting the golf ball
In this case the action will be the force of the club hitting the golf ball and reaction will be the force acting on club due to golf ball
∴ The club pushes against to golf ball with a force equal and opposite to the force of the golf ball on the club
Answer:
6370 J
Explanation:
By the law of energy conservation, the work done by the student would be the change in potential enegy from 1st floor to 3rd floor, or a change of 13 m

where m = 50kg is the mass of the student, g = 9.8 m/s2 is the gravitational constant and h = 13 m is the height difference

Answer:
The time is 
The speed is 
Explanation:
From the question we are told that
The height of the cliff is 
Generally from kinematic equation we have that

before the jump the persons initial velocity is u = 0 m/s
So

=> 
Generally from kinematic equation

=> 
=> 
The height difference is found by

Then the change in potential energy is