a packing ccrate slides down an incline ramp at constant velocity. Thus we can deduce that
a) a frictional force is acting on it
b) a net downward force is acting on it
c) it may be accelerating
d) it is not acted on by appreciable gravitational force
with a constant velocity isn't there frictional force acting on it so the correct answer would be a)? I do know that d) is wrong.
If the velocity is constant, as given, then there is no net acceleration and so no net force. That eliminates two answers.
I agree: the word net in b) makes it wrong. Velocity is constant.
Yes, you are correct. If the packing crate is sliding down an incline ramp at a constant velocity, it means there must be a frictional force acting on it to counteract the force pulling it downhill. Therefore, the correct answer would be option a) - a frictional force is acting on it.
Option b) - a net downward force is acting on it, is incorrect because if the crate is moving at a constant velocity, it means that the forces acting on it are balanced, so there is no net downward force.
Option c) - it may be accelerating, is also incorrect because if the crate is moving at a constant velocity, it is not changing its speed or direction, so there is no acceleration.
Option d) - it is not acted on by appreciable gravitational force, is also incorrect because gravity is still acting on the crate, but it is being balanced by the frictional force.
You are correct to eliminate option d) because the crate is sliding down an incline, so it is definitely acted upon by a gravitational force. Now, let's consider the other options.
If the crate is sliding down the incline at a constant velocity, this means that its acceleration is zero. Since acceleration is the rate of change of velocity, a zero acceleration implies that there is no net force acting on the crate in the horizontal direction (along the incline).
Option b) suggests that there is a net downward force acting on the crate. However, if the velocity of the crate is constant, it means that the upward force balancing the crate's weight is equal in magnitude to the downward force of gravity.
This brings us to option a) - a frictional force acting on the crate. When the crate slides down the incline at constant velocity, it indicates that there is a frictional force opposing the motion of the crate. This frictional force counteracts the component of the gravitational force down the incline, preventing the crate from accelerating.
Therefore, the correct answer is a) a frictional force is acting on it.
To summarize, when a packing crate slides down an incline ramp at constant velocity, we deduce that there is a frictional force acting on it, which exactly balances the gravitational force component down the incline to maintain a constant velocity.