If a ball is thrown vertically upwards with a velocity of `40m//s`, then velocity of the ball after `2s` will be `(g = 10m//s^(2))`

Options

A. `15m//s`
B. `20 m//s`
C. `25m//s`
D. `28 m//s`

Answer

To solve the problem of finding the velocity of a ball thrown vertically upwards after 2 seconds, we can use the equations of motion. Here’s a step-by-step solution:

### Step 1: Identify the given values
- Initial velocity (U) = 40 m/s (upwards)
- Acceleration (a) = -10 m/s² (downwards, since gravity acts in the opposite direction to the motion)
- Time (t) = 2 s

### Step 2: Use the equation of motion
We can use the first equation of motion:
\[ V = U + a \cdot t \]
where:
- V = final velocity
- U = initial velocity
- a = acceleration
- t = time

### Step 3: Substitute the values into the equation
Substituting the known values into the equation:
\[ V = 40 \, \text{m/s} + (-10 \, \text{m/s}^2) \cdot (2 \, \text{s}) \]

### Step 4: Calculate the acceleration term
Calculate the product of acceleration and time:
\[ -10 \, \text{m/s}^2 \cdot 2 \, \text{s} = -20 \, \text{m/s} \]

### Step 5: Substitute back into the equation
Now substitute this back into the equation for V:
\[ V = 40 \, \text{m/s} - 20 \, \text{m/s} \]

### Step 6: Final calculation
Now perform the final calculation:
\[ V = 20 \, \text{m/s} \]

Thus, the velocity of the ball after 2 seconds is **20 m/s** upwards.

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