Answer:
The mass of the child + skateboard is 50 kg
Explanation:
In this problem, we can apply Newton's second law:
F = ma
where
F is the net force on a system
m is the mass of the system
a is the acceleration of the system
In this problem, our system is the child + the skateboard. The net force on them is
F = 75 N
and their acceleration is

So we can re-arrange the equation above to find their combined mass:

The net force will point towards the acceleration of the object, as supported by Newton's second law.
Answer:
The horizontal velocity is 
Explanation:
From the question we are told that
The mass of the pumpkin is 
The distance of the the car from the building's base is 
The height of the roof is 
The height is mathematically represented as

Where g is the acceleration due to gravity which has a value of 
substituting values

making the time taken the subject of the formula


The speed at which the pumpkin move horizontally can be represented mathematically as

substituting values


Answer:
A. 26.17 B. 1.17 C. 30.86 D. 5.86
Explanation:
Answer:
120 J
Explanation:
KE = mv²/2 = (0.15 kg * [40 m/s]²)/2 = 120 J