Answer:
Explanation:
Length if the bar is 1m=100cm
The tip of the bar serves as fulcrum
A force of 20N (upward) is applied at the tip of the other end. Then, the force is 100cm from the fulcrum
The crate lid is 2cm from the fulcrum, let the force (downward) acting on the crate be F.
Using moment
Sum of the moments of all forces about any point in the plane must be zero.
Let take moment about the fulcrum
100×20-F×2=0
2000-2F=0
2F=2000
Then, F=1000N
The force acting in the crate lid is 1000N
Option D is correct
Answer:
The ground exerts an equal force on the golf ball
Explanation:
Third's Newton Law states that:
"When an object A exerts a force on an object B, then object B exerts an equal and opposite force on object A".
In this problem, object A is the golf ball while object B is the ground, so we can say that:
- the golf ball exerts a force on the ground
- the ground exerts an equal and opposite force on the golf ball
The braking force is -400 N
Explanation:
We can solve this problem by using the impulse theorem, which states that the impulse applied on the ferry (the product of force and time) is equal to its change in momentum:

where in this problem, we have:
F is the force applied by the brakes
is the time interval
m = 13,000 kg is the mass of the ferry
u = 2.0 m/s is the initial velocity
v = 0 is the final velocity
And solving for F, we find the force applied by the brakes:

where the negative sign indicates that the direction is backward.
Learn more about impulse:
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To solve this problem we will start from the definition of energy of a spring mass system based on the simple harmonic movement. Using the relationship of equality and balance between both systems we will find the relationship of the amplitudes in terms of angular velocities. Using the equivalent expressions of angular velocity we will find the final ratio. This is,
The energy of the system having mass m is,

The energy of the system having mass 2m is,

For the two expressions mentioned above remember that the variables mean
m = mass
Angular velocity
A = Amplitude
The energies of the two system are same then,



Remember that

Replacing this value we have then


But the value of the mass was previously given, then



Therefore the ratio of the oscillation amplitudes it is the same.