Air from a balloon does not need to touch anything in order for the balloon to move. The outside forces around the balloon push down it so it contracts and air is expelled. This propulsion is what moves the balloon.
Warmer air has molecules more spread out, so I'd say a decrease in air pressure.
Answer:
(1) Exercise should be painful in order for it to be beneficial. FALSE
(2) Proper progression involves a gradual increase in the level of exercise. TRUE
(3) Exercising on a regular, consistent basis provides you with the best results. TRUE
Explanation:
(1) It is a false statement because whenever we do exercise, it should not be painful, it should be comfortable to some extent for a person, if it will be painful then it means one cant get the true and genuine benefit from the exercise.
(2) It is very much true because one must keep on increasing the level of his/her exercise gradually with the passage of time, it will make his/her body synchronized with the exercise properly.
(3) It is also a true statement because, one must use variety of exercises in his/her workout session targeting different muscles and different areas and parts of the body to make exercise really beneficial.
Explanation:
The dimension of the book is 1.75 m × 2.25 m. If the book ends up at its initial position. The displacement of the book is equal to zero as the object reaches to its initial position.
If it completes its motion in 23 s, t = 23 s
Total displacement of the book is equal to its perimeter. It is given by :

The net displacement divided by total time taken is called the average velocity of an object. Here, the displacement is 0. So, average velocity is 0.
The average speed of an object is given by :


v = 0.347 m/s
So, the average speed of the book is 0.347 m/s. Hence, this is the required solution.
Answer: option D) 42.4 N
The weight of the frame is balanced by the vertical component of tension.
W = T sin θ + T sin θ = 2 T sin θ
The tension in each cable is T = 30 N
Angle made by the cables with the horizontal, θ = 45°
⇒ W = 2×30 N × sin 45° = 2 × 30 N × 0.707 = 42.4 N
Hence, the weight of the frame is 42.4 N. Correct option is D.