To find the acceleration of the sled, you can use the formula:
F = ma
where F is the applied force, m is the mass of the object, and a is the acceleration.
In this case, you know the applied force and the mass of the sled, so you can solve for the acceleration.
First, you need to find the horizontal component of the applied force. You can do this using the formula:
F_horizontal = F * cos(θ)
where F_horizontal is the horizontal component of the applied force, F is the applied force, and θ is the angle at which the force is applied.
Plugging in the given values, you get:
F_horizontal = 21 N * cos(30°) = 18.5 N
Then, you can use the formula for acceleration to solve for the acceleration of the sled:
a = F_horizontal / m = 18.5 N / 15 kg = 1.23 m/s^2
So the acceleration of the sled is approximately 1.23 m/s^2.
It's important to note that this calculation assumes that there is no friction acting on the sled. If there is friction present, the actual acceleration of the sled may be different.