Answer:
a = 0.1962 m/s^2
Explanation:
The magnitude of kinetic friction exerted is given by

Where, μ_k= coefficient of kinetic friction= 0.02 and N = reaction force = mg
Where m= mass = 30 Kg and, g is acceleration due to gravity =9.81 m/s^2
F_k=0.02×30×9.81 =5.886 N
Now, since, there is no applied force this kinetic friction force will cause acceleration of the child
⇒ ma = F_k
here, a is the acceleration
⇒30a = 5.886
⇒ a = 0.1962 m/s^2
Answer:
The initial speed of the bullet is
.
Explanation:
The collision between bullet and block is inelastic and let suppose that motion occurs on a horizontal surface, so that changes in gravitational potential energy can be neglected. Initially, the intial speed of the bullet-block system can be determined with the help of the Work-Energy Theorem and the Principle of Energy Conservation:


The initial speed of the bullet-block system is:

Now, the initial speed of the bullet is determined by applying the Principle of Momentum Conservation:


We will assume that the CM of the arm is at "L"
from the elbow, and the ball is at 34cm. Then the net torque is computed
by:
Net τ = 1.42 N * 34 cm + 1.50 kg * 9.8m/s² * 34 cm/2 – 12.6 N*2.75cm
= 48.28 N*cm + 1.50kg * 9.8m/s² * 34 cm/2 – 12.6 N*2.75cm
= 48.28 N*cm + 499.8 – 34.65 N*cm
τ = 513.43 N*cm or
5.1343 N*m