Answer:
Explanation:
Given
height of grand canyon is 
Rock is dropped i.e. initial velocity is zero

Using Equation of motion

h=height
u=initial velocity
a=acceleration
t=time
here a=acceleration due to gravity


Answer:
(a) 
(b) 
Explanation:
mass, m = 2.3 kg
vx = 40 m/s
vy = 75 m/s
(a) Angular momentum is given by

Where, p is the linear momentum and r is the position vector about which the angular momentum is calculated.
Here, 



So, the angular momentum


(b) Here, 



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Answer:
c. The coefficient of kinetic friction is less than the coefficient of static friction
Explanation:
When the box finally does break loose. Then the component of the box weight which is parallel to the board weight parallel component, is equal to the
.

For the box to acce;erate thee must be non-zero net force acting on the box parallel to the board. Or we can say,

Therefore the force of kinetic friction must be less than the force of static friction. Thus,

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