Answer:
The speed of the plank is 81.68 m/s
Explanation:
Given that,
Speed of bullet = 152 m/s
Speed of wood = 128 m/s
Speed of another bullet = 97 m/s
We need to calculate the speed of plank
Using conservation of momentum

Where,
u = initial velocity
v = final velocity
....(I)
....(II)
From equation(I) and equation(II)



Hence, The speed of the plank is 81.68 m/s
Answer:
B. The two sleds will move to the right.
Explanation:
I majored in physics
Answer:
The radius of the sphere is 4.05 m
Explanation:
Given;
potential at surface,
= 450 V
potential at radial distance,
= 150
radial distance, l = 8.1 m
Apply Coulomb's law of electrostatic force;


Therefore, the radius of the sphere is 4.05 m
Answer:
The motion of the ball relative to the ground is stationary
The motion of the ball relative to the wagon is backwards
Explanation:
To describe the motion of the ball relative to the ground, we note that
Assuming the ball is perfectly round and rotate freely, then we have
Force on the ball due to motion of the wagon = 0 N,
Then by the law of motion, an object will remain at rest when no force is applied to it
Therefore, apart from rotation of the ball, it will remain no displacement relative to the ground.
The motion of the ball relative to the wagon
Relative to the wagon, the ball appears to be moving in the opposite direction to the wagon, that is backwards.
Answer:
70.15 Joule
Explanation:
mass of man, m = 70 kg
intial length, l = 11 m
extension, Δl = 1.5 m
Let K is the spring constant.
In the equilibrium position
mg = K l
70 x 9.8 = K x 11
K = 62.36 N/m
Potential energy stored, U = 0.5 x K x Δl²
U = 0.5 x 62.36 x 1.5 x 1.5
U = 70.15 Joule