Answer:
78.4 m
Explanation:
To obtain the height of the cliff;
We can use the Relation to obtain the final velocity, v
v = u + at
a = acceleration due to gravity = 9.8m/s²
v = 0 + (9.8*4)
v = 0 + 39.2
v = 39.2 m/s
To obtain the Height, S
v² = u² + 2aS
39.2^2 = 0 + 2(9.8)S
39.2^2 = 0 + 19.6S
1536.64 = 19.6S
S = 1536.64 / 19.6
S = 78.4 m
Answer:
False
Explanation:
The given statement "Two objects must be in contact for them to exert a force on each other" is not true as there are many types of forces that doesn't require being in contact for exerting a force.
One such example is the gravitational force acting between two bodies. Gravitational force is the force of pull with which a body pulls another body without being in contact.
For two bodies of masses 'M' and 'm' separated at a distance of 'R', the gravitational force is given as:

The gravitational force acts always act between bodies that have mass. The bodies are not in contact yet experience force.
Therefore, the given statement is false.
The total mechanical energy of the block-spring system is given by the sum of the potential energy and the kinetic energy of the block:

where
k is the spring constant
x is the elongation/compression of the spring
m is the mass of the block
v is the speed of the block
At the point of maximum displacement of the spring, the velocity of the block is zero: v=0, so the kinetic energy is zero and the mechanical energy is just potential energy of the spring:

(1)
where we used x=A, the amplitude (which is the maximum displacement of the spring).
Since we know
A = 11.0 cm= 0.11 m
E = 1.10 J
We can re-arrange (1) to find the spring constant:
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