Question

A centripetal acceleration can a) Change an object’s direction. b) Change an object’s speed.

A tangential acceleration can a) Change an object’s direction. b) Change an object’s speed.

An object moves in a straight line at a constant speed ___________________.

An object moves in a circle at a constant speed_________________________.

An object moves in a straight line while slowing to a stop _________________.

The acceleration… a. Points parallel to the velocity, and in the same direction. b. Points parallel to the velocity, but in the opposite direction. c. Points radially inward. d. Points radially outward. e. Is zero.

Answer 1

1>Centripetal acceleration changes object direction.

Explanation:

Can an object accelerate if it's moving with constant speed? Yup! Many people find this counter-intuitive at first because they forget that "changes in the direction of motion of an object"—even if the object is maintaining a constant speed—still count as acceleration.

Acceleration is a change in velocity, either in its magnitude—i.e., speed—or in its direction, or both. In uniform circular motion, the direction of the velocity changes constantly, so there is always an associated acceleration, even though the speed might be constant. You experience this acceleration yourself when you turn a corner in your car—if you hold the wheel steady during a turn and move at constant speed, you are in uniform circular motion. What you notice is a sideways acceleration because you and the car are changing direction. The sharper the curve and the greater your speed, the more noticeable this acceleration will become.

Figure shows ,The directions of the velocity of an object at two different points are shown, and the change in velocity Δv is seen to point directly toward the center of curvature. (See small inset.) Because ac = Δv/Δt, the acceleration is also toward the center; ac is called centripetal acceleration. (Because Δθ is very small, the arc length Δs is equal to the chord length Δr for small time differences.)

2>Tangential acceleration changes object Speed.

Explanation:

In uniform circular motion, the particle executing circular motion has a constant speed and the circle is at a fixed radius. If the speed of the particle is changing as well, then we introduce an additional acceleration in the direction tangential to the circle. Such accelerations occur at a point on a top that is changing its spin rate, or any accelerating rotor. In Displacement and Velocity Vectors we showed that centripetal acceleration is the time rate of change of the direction of the velocity vector. If the speed of the particle is changing, then it has a tangential acceleration that is the time rate of change of the magnitude of the velocity:

aT=d|→v|dt.

3>Object moving ina straight line with constant speed then it has Zero acceleration.

Explanation:

Motion with constant velocity is one of the simplest forms of motion. This type of motion occurs when an an object is moving (or sliding) in the presence of little or negligible friction, similar to that of a hockey puck sliding across the ice. To have a constant velocity, an object must have a constant speed in a constant direction. Constant direction constrains the object to motion to a straight path.

Newton’s second law (F=maF=ma) suggests that when a force is applied to an object, the object would experience acceleration. If the acceleration is 0, the object shouldn’t have any external forces applied on it. Mathematically, this can be shown as the following:

a=dvdt=0 ⇒ v=consta=dvdt=0 ⇒ v=const.

4>object moving in circle with constant speed ,here the acceleration is non zero and it is Centripetal acceleration which acts towards the centre of circle.

5>object moving in a straight line while slowing to stop ;here the acceleration is non zero because it has different velocities at the beginning and end as rate of change of velocity gives acceleration,and here the acceleration is known as "Deceleration "and it is in the opposite direction of velocity .

6>we know that acceleration is in the direction of change in velocity ,although "acceleration" is in the direction of the change in velocity, it is not always in the direction of motion. When an object slows down, its acceleration is opposite to the direction of its motion. This is known as "deceleration".

If the acceleration is" centripetal" then it acts radially inwards.

The acceleration is zero when object moves with constant speed in a straight line.