Answer: Statement 1 is incorrect.
Reason:
Unit of measure of angular distance is not meters.
Explanation:
The term 'angular size' is used to describe the apparent size of the objects in the night sky.
The angular distance is defined as the angle through which an object moves on a circular path. The SI unit is radian.
Other units are revolution (rev) and degrees.
In statement 1, angular distance is measured in meters which is incorrect. In other options, there is no factual mistake so they are correct.
Let's discuss them,
Statement 2:
Here, we are talking about the use of outstretched hand to estimate the angular distances and sizes which is correct.
Statement 3:
This statement talks about the same angular sizes of the sun and the moon, here the term is again used correctly.
Statement 4:
Here, the angular distance is measured in the correct units i.e, degrees so this statement is also correct.
Answer:
All parts of a wheel rotating about a fixed axis must have the same angular speed.
All parts of a wheel rotating about a fixed axis must have the same angular acceleration.
Explanation:
In a rigid body in rotation (a rotating wheel) with respect to a fixed axis, each particle on the body turns around the same angle in a certain time interval, having the same angular speed and the same angular acceleration. Otherwise, the wheel will deform, therefore it would not be in equilibrium
The efficiency of the bicycle is 20% because 200 out 100 is 2.and ,convert 1000 j out 100 that equal to 10 but,then multiply 2×10 that equal to 20%