you throw a rock straight up at 30m/s, how fast will it be moving 2 sec later? No friction?

Answer 1

10.4 m/sec

V(t) = (30+a*t) m/sec

where a = - 9.8m/sec^2

V(2) = (30 - 09.8*2) m/sec

V(2) = 30-19.6 = 10.4 m/sec

Answer 2

The acceleration due to gravity is 9.8 (m/s)/s.

It means every second the velocity is increasing by a value 9.8m/s in every second.

If a body is thrown up its velocity will reduce by 9'8m/s in every second.

Thus in 2 second its speed will reduce by an amount 2 x9.8 = 19.6 m/s.

Since the initial speed was 30m/s, after 2 second it speed will be 30 - 19.6 = 10.4 m/s of course in the upward direction.


Mathematically we use this formula to find the final velocity.


V = U + a T.


U is the initial velocity in the upward direction = 30m/s.

a = the acceleration due to gravity in the down ward direction = -9.8 (m/s) /s.

T is the time of travel = 2 second.

V = 30 - 2 x 9.8 = 10.4 m/s in the upward direction.

Answer 3

The force of gravity acting on the rock would cause it to accelerate towards the earth at a rate of 10m/s/s. In each second it acts on the rock, gravity reduces the rock's speed by 10m/s. Therefore, in 2 seconds gravity reduces the speed of the rock by 20m/s. Thus, the speed of the rock after 2 seconds is 10m/s.

Answer 4

if u throw a rock straight at 30m/s it will be moving slower than the original speed, in 2 seconds later cos ,the gravity on th rock will reduce

Answer 5

It'll be moving at approximately 10m/s.
Objects near Earth's surface are pulled toward Earth at about 10m/s^2 from Earth's gravitational pull. So if you throw a rock in the air it will lose speed (decelerate) until it reaches 0m/s, when it will start speeding up again as it falls back to Earth.

Answer 6

It'll be slower- the air will slow it down

if you chuck it in space (no friction) - it'll stay the same speed forever