Answer:
The force parallel to the horizontal is 26.24 N
Explanation:
She pulls on the leash with a force F = 30 N, this force, since its at an angle of 29° (i will cal this angle 
), it has a force component on x (the horizontal, i will call this force 
) and a force component on y (the vertical, i will call this 
).
This can be seen in the attached picture.
Since we are asked about the force parallel to the horizontal, we need to find the component of the force , since is the adjacent angle, we need to use cosine:
since 
and 
The force parallel to the horizontal is 26.24 N
Answer:
21.21 m/s
Explanation:
Let KE₁ represent the initial kinetic energy.
Let v₁ represent the initial velocity.
Let KE₂ represent the final kinetic energy.
Let v₂ represent the final velocity.
Next, the data obtained from the question:
Initial velocity (v₁) = 15 m/s
Initial kinetic Energy (KE₁) = E
Final final energy (KE₂) = double the initial kinetic energy = 2E
Final velocity (v₂) =?
Thus, the velocity (v₂) with which the car we travel in order to double it's kinetic energy can be obtained as follow:
KE = ½mv²
NOTE: Mass (m) = constant (since we are considering the same car)
KE₁/v₁² = KE₂/v₂²
E /15² = 2E/v₂²
E/225 = 2E/v₂²
Cross multiply
E × v₂² = 225 × 2E
E × v₂² = 450E
Divide both side by E
v₂² = 450E /E
v₂² = 450
Take the square root of both side.
v₂ = √450
v₂ = 21.21 m/s
Therefore, the car will travel at 21.21 m/s in order to double it's kinetic energy.
