Here easy answer from online
In scientific contexts, mass is the amount of "matter" in an object (though "matter" may be difficult to define), whereas weight is the force exerted on an object by gravity.
Answer
given,
distance = 140 m
time, t = 3.6 s
moving speed = 53 m/s
a) distance = (average velocity) x time


v₀ + 53 = 77.78
v₀ = 24.78 m/s or 25 m/s
b) 

a = 7.8 m/s²
using equation of motion
v₀² = v₁² + 2 a s
53² = 0²+ 2 x 7.8 x s
s = 180 m
Answer:
25J
Explanation:
Given parameters:
Mass of the dog = 10kg
Speed of the dog = 5m/s
Unknown:
The minimum energy required to stop the dog = ?
Solution:
The dog is moving with a kinetic energy and to stop the dog, an equal amount of kinetic energy generated must be applied to the dog.
To find the kinetic energy;
K.E =
m v²
m is the mass
v is the velocity
Now insert the parameters and solve;
K.E =
x 10 x 5 = 25J
Answer:
One positive and one negative