That is b. hope this helps cx
        
             
        
        
        
Answer:
At point A, the cart has high potential energy. At point b, the cart is pulled down by gravity. At point c, the cart gains its highest kinetic energy. At point d, the cart returns back to the same state but with lower potential energy.
 
        
             
        
        
        
Answer:
Except in the crust, the interior of the Earth cannot be studied by drilling holes to take samples. Instead, scientists map the interior by watching how seismic waves from earthquakes are bent, reflected, sped up, or delayed by the various layers.
Explanation:
 
        
             
        
        
        
Hello
Here we must use the equation of motion 
v^2 = u^2 + 2as; where v is final velocity, u is initial velocity, a is the acceleratoin and is the distance travelled.
We select this one because the time of collision is unknown to us.
We know the truck stopped so its final velocity is 0; thus v = 0.
Converting the initial velocity to SI units, we get 3.89 m/s.
The distance traveled, s, is 0.062 meters.
Inserting all of these values into the equation,
0 = (3.89)^2 + 2(a)(0.062)
and solving for a, we get a to be
-122.0 ms^(-2)
The negative sign indicates the acceleration is in the opposite direction to the initial motion, which means the truck decelerated. This is consistent with the given condition.