Using the equation

we can observe that you have to apply a non-zero net force to an object in order to make it accelerate. In fact, if the net force is zero you have

Since we're assuming 
Now, if the 12N force is applied, the object moves with a constant speed. A constant speed means no acceleration, since by definition the acceleration is a change in speed.
If this sounds counterintuitive to you (why I'm applying a force but I have to acceleration?) think of when we drive a car: even if you want to keep your speed constant, you still have to use the gas pedal, just enough so that the push of the motor balances exactly the road/wheels friction. If you give less gas, the friction becomes stronger, and the car slows down. If you give more gas, the motor push becomes stronger, and the car accelerates.
Back to your exercise: constant speed means to acceleration, so the net force must be zero. This implies that the friction force is exactly 12N.
If the force is increased to 18N, there will be a net force of 6N pushing the object, causing it to accelerate. Using again the same equation of before, and plugging the 3kg mass in the equation, we have

So, the object moves with constant acceleration and initial speed of 10m/s for 0.2 seconds. It's final speed will be

The force that pulls the wagon is the horizontal component of the actual force, which is 290*cos(32) = 246N
We have thatThe options that define Speed, Velocity,Acceleration.
- Speed is used to describe how fast the object is moving.
- Acceleration is the rate of change of velocity in time.
- Velocity is used to describe how fast the object is moving and tells us in which direction it is going.
Options
B,D,E
From the question we are told
Choose the correct definitions of speed, velocity, and acceleration. Check all that apply.
- Acceleration tells us in which direction the object is going. Speed is the rate of change of velocity in time.
- Acceleration is the rate of change of velocity in time.
- Velocity is used to describe changes in the movement direction of the object. Acceleration tells us how far the object will go in a certain amount of time.
- Velocity is used to describe how fast the object is moving and tells us in which direction it is going.
- Speed is used to describe how fast the object is moving.
- Velocity is the rate of change of speed in time.
Speed is used to describe how fast the object is moving and tells us in which direction it is going.
Generally
- Acceleration is the rate of change of velocity in time.
- Velocity is used to describe how fast the object is moving and tells us in which direction it is going.
- Speed is used to describe how fast the object is moving without its direction in consideration
Hence
The options that define Speed, Velocity,Acceleration.
- Speed is used to describe how fast the object is moving.
- Acceleration is the rate of change of velocity in time.
- Velocity is used to describe how fast the object is moving and tells us in which direction it is going.
Options
B,D,E
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The answer is D.<span>longitudinal</span>
They can.
Surfers use waves to move themselves around.