Answer:
the 70kg man
Explanation:
because he has more weight and is moving faster
Answer:(a)891.64 N
(b)0.7
Explanation:
Mass of crate 
Crate slows down in 
initial speed 
inclination 
From Work-Energy Principle
Work done by all the Forces is equal to change in Kinetic Energy




change in kinetic energy

(b)Coefficient of sliding friction



and 


Answer:
upwards
Explanation:
Torque is the vector cross product of the force and radial distance.


The direction of the torque would be perpendicular to the direction of the force and radial distance. The direction of the force is counter-clockwise. The direction of the torque would be upwards.
Answer : The restoring force is directly proportional to the displacement of the block.
Explanation :
Restoring force is defined as the force that is exerted by the spring due to its mass.
Mathematically, the restoring force can be written as :

F = - k x
where,
k is the spring constant.
x is the displacement caused due to the mass.
Negative sign shows that the force is acting in opposite direction.
So, it is clear that the restoring force is directly proportional to the displacement of the block.
Hence, the correct option is (b) " The restoring force is directly proportional to the displacement of the block ".
Answer:
a) L = 0.75m f₁ = 113.33 Hz
, f₃ = 340 Hz, b) L=1.50m f₁ = 56.67 Hz
, f₃ = 170 Hz
Explanation:
This resonant system can be simulated by a system with a closed end, the tile wall and an open end where it is being sung
In this configuration we have a node at the closed end and a belly at the open end whereby the wavelength
With 1 node λ₁ = 4 L
With 2 nodes λ₂ = 4L / 3
With 3 nodes λ₃ = 4L / 5
The general term would be λ_n= 4L / n n = 1, 3, 5, ((2n + 1)
The speed of sound is
v = λ f
f = v / λ
f = v n / 4L
Let's consider each length independently
L = 0.75 m
f₁ = 340 1/4 0.75 = 113.33 n
f₁ = 113.33 Hz
f₃ = 113.33 3
f₃ = 340 Hz
L = 1.5 m
f₁ = 340 n / 4 1.5 = 56.67 n
f₁ = 56.67 Hz
f₃ = 56.67 3
f₃ = 170 Hz