Answer:
Newtons first law
Explanation:
object in rest stays at rest
object in motion stays in motion
Answer:
The force needs to be applied on the 1 square meter piston to lift the machine is 200 N.
Explanation:
Given that,
Force, 
Area, 
We need to find the force needs to be applied on the 1 square meter piston to lift the machine. We know that the pressure at every point is same due to Pascal's law such that :

So, the force needs to be applied on the 1 square meter piston to lift the machine is 200 N. Hence, this is the required solution.
1) c. 2 m/s
Explanation:
The relationship between frequency, wavelength and speed of a wave is

where
v is the speed
is the wavelength
f is the frequency
For the wave in this problem,
f = 4 Hz

So, the speed is

2) a. 2.8 m/s
The speed of the wave on a string is given

where
T is the tension in the string
is the linear mass density
In this problem, we have:
(final tension in the rope, which is twice the initial tension)
--> mass density of the rope
Substituting into the formula, we find

Option C would be the right one
In a problem where a child is danger form drowning from a river who has a current of 3.1km/hr to east and the child is 0.6km fro the shore and the upstream is 2,5km from the dock. So base on the question the boat with a speed of 24.8 km/hr is 1.9 km because the child is 0.6 km off the dock so 2.5 minus 0.6