A rock from a volcanic eruption is launched straight up into the air with no app

Question

A rock from a volcanic eruption is launched straight up into the air with no appreciable air resistance. Which one of the following statements about this rock while it is in the air is correct? A) On the way up, its acceleration is downward and its velocity is upward, and at the highest point both its velocity and acceleration are zero. B) Throughout the motion, the acceleration is downward, and the velocity is always in the same direction as the acceleration. C) The acceleration is downward at all points in the motion except that is zero at the highest point. D) The acceleration is downward at all points in the motion. Position x, in meters (m), of an object is given by equation x = At^-2 + Bt + Ct^-1, where t represents time in seconds (s). Fill in each of the blanks for the SI units of A, B, and C? What is the result to the proper number of significant figures for 0.674/0.74? A) 0.9 B) 0.911 C) 0.9108 D) 0.91 You are trying to cross a river that flows toward the south with a strong current. You start out in your motorboat on the east bank desiring to reach the west bank directly west from your starting point. You should head your motorboat A) directly toward the west. B) directly toward the north. C) in a general southwesterly direction. D) in a general northwesterly direction. When an object is released from rest and falls in the absence of friction, which of the following is true concerning its motion? A) Both its acceleration and its velocity are constant. B) Its velocity is increasing and its acceleration is constant. C) Neither its acceleration nor its velocity is constant. D) Its velocity is constant and its acceleration is increasing.

Explanation / Answer

I-1)
acceleration acting on the rock is acceleration due to gravity.
Acceleration due to gravity always acts downward
Answer: D

I-2)
A)
A*t^-2 should have unit of m
A*s^-2 should have unit of m
A will have unit of m.s^2

B)
B*t should have unit of m
B*s should have unit of m
B will have unit of m/s

C)
C*t^-1 should have unit of m
C*s^-1 should have unit of m
C will have unit of m.s

I-3)
0.674/0.74 will have 2 significant figure since 0.74 has 2 significant figures
so,
0.674/0.74 = 0.91
Answer: 0.91

I am allowed to answer only 1 question at a time

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